DSpace at VNU: Observation of the rare B-s(0)- mu(+)mu(-) decay from the combined analysis of CMS and LHCb data

LETTER OPEN doi:10.1038/nature14474 Observation of the rare Bs0Rm1m2 decay from the combined analysis of CMS and LHCb data The CMS and LHCb collaborations* The standard model of particle physics describes the fundamental particles and their interactions via the strong, electromagnetic and weak forces It provides precise predictions for measurable quantities that can be tested experimentally The probabilities, or branching fractions, of the strange B meson (Bs0 ) and the B0 meson decaying into two oppositely charged muons (m1 and m2) are especially interesting because of their sensitivity to theories that extend the standard model The standard model predicts that the Bs0 ?m1m2 and B0 ?m1m2 decays are very rare, with about four of the former occurring for every billion Bs0 mesons produced, and one of the latter occurring for every ten billion B0 mesons1 A difference in the observed branching fractions with respect to the predictions of the standard model would provide a direction in which the standard model should be extended Before the Large Hadron Collider (LHC) at CERN2 started operating, no evidence for either decay mode had been found Upper limits on the branching fractions were an order of magnitude above the standard model predictions The CMS (Compact Muon Solenoid) and LHCb (Large Hadron Collider beauty) collaborations have performed a joint analysis of the data from proton–proton collisions that they collected in 2011 at a centre-ofmass energy of seven teraelectronvolts and in 2012 at eight teraelectronvolts Here we report the first observation of the Bs0 ? m1m2 decay, with a statistical significance exceeding six standard deviations, and the best measurement so far of its branching fraction Furthermore, we obtained evidence for the B0 ? m1m2 decay with a statistical significance of three standard deviations Both measurements are statistically compatible with standard model predictions and allow stringent constraints to be placed on theories beyond the standard model The LHC experiments will resume taking data in 2015, recording proton–proton collisions at a centre-of-mass energy of 13 teraelectronvolts, which will approximately double the production rates of Bs0 and B0 mesons and lead to further improvements in the precision of these crucial tests of the standard model Experimental particle physicists have been testing the predictions of the standard model of particle physics (SM) with increasing precision since the 1970s Theoretical developments have kept pace by improving the accuracy of the SM predictions as the experimental results gained in precision In the course of the past few decades, the SM has passed critical tests derived from experiment, but it does not address some profound questions about the nature of the Universe For example, the existence of dark matter, which has been confirmed by cosmological data3, is not accommodated by the SM It also fails to explain the origin of the asymmetry between matter and antimatter, which after the Big Bang led to the survival of the tiny amount of matter currently present in the Universe3,4 Many theories have been proposed to modify the SM to provide solutions to these open questions The B0s and B0 mesons are unstable particles that decay via the weak interaction The measurement of the branching fractions of the very rare decays of these mesons into a dimuon (m1m2) final state is especially interesting At the elementary level, the weak force is composed of a ‘charged current’ and a ‘neutral current’ mediated by the W6 and Z0 bosons, respectively An example of the charged current is the decay of the p1 meson, which consists of an up (u) quark of electrical charge 12/3 of the charge of the proton and a down (d) antiquark of charge 11/3 A pictorial representation of this process, known as a Feynman diagram, is shown in Fig 1a The u and d quarks are ‘first generation’ or lowest mass quarks Whenever a decay mode is specified in this Letter, the charge conjugate mode is implied The B1 meson is similar to the p1, except that the light d antiquark is replaced by the heavy ‘third generation’ (highest mass quarks) beauty (b) antiquark, which has a charge of 11/3 and a mass of ,5 GeV/c2 (about five times the mass of a proton) The decay B1R m1n, represented in Fig 1b, is allowed but highly suppressed because of angular momentum considerations (helicity suppression) and because it involves transitions between quarks of different generations (CKM suppression), specifically the third and first generations of quarks All b hadrons, including the B1, B0s and B0 mesons, decay predominantly via the transition of the b antiquark to a ‘second generation’ (intermediate mass quarks) charm (c) antiquark, which is less CKM suppressed, into final states with charmed hadrons Many allowed decay modes, which typically involve charmed hadrons and other particles, have angular momentum configurations that are not helicity suppressed The neutral B0s meson is similar to the B1 except that the u quark is replaced by a second generation strange (s) quark of charge 21/3 The decay of the B0s meson to two muons, shown in Fig 1c, is forbidden at the elementary level because the Z0 cannot couple directly to quarks of different flavours, that is, there are no direct ‘flavour changing neutral currents’ However, it is possible to respect this rule and still have this decay occur through ‘higher order’ transitions such as those shown in Fig 1d and e These are highly suppressed because each additional interaction vertex reduces their probability of occurring significantly They are also helicity and CKM suppressed Consequently, the branching fraction for the B0s ?mz m{ decay is expected to be very small compared to the dominant b antiquark to c antiquark transitions The corresponding decay of the B0 meson, where a d quark replaces the s quark, is even more CKM suppressed because it requires a jump across two quark generations rather than just one The branching fractions, B, of these two decays, accounting for higher-order electromagnetic and strong interaction effects, and using lattice quantum chromodynamics to compute the B0s and B0 meson decay constants5–7, are reliably calculated1 in the SM Their values are B(B0s ?mz m{ )SM ~(3:66+0:23)|10{9 and B(B0 ?mz m{ )SM ~ (1:06+0:09)|10{10 Many theories that seek to go beyond the standard model (BSM) include new phenomena and particles8,9, such as in the diagrams shown in Fig 1f and g, that can considerably modify the SM branching fractions In particular, theories with additional Higgs bosons10,11 predict possible enhancements to the branching fractions A significant deviation of either of the two branching fraction measurements from the SM predictions would give insight on how the SM should be extended Alternatively, a measurement compatible with the SM could provide strong constraints on BSM theories *Lists of participants and their affiliations appear in the online version of the paper 0 M O N T H | VO L 0 | N AT U R E | G2015 Macmillan Publishers Limited All rights reserved RESEARCH LETTER The ratio of the branching fractions of the two decay modes provides powerful discrimination among BSM theories12 It is predicted in the SM (refs 1, 13 (updates available at http://itpwiki.unibe.ch/), 14, 15 (updated results and plots available at http://www.slac.stanford edu/xorg/hfag/)) to be R:B(B0 ?mz m{ )SM =B(B0s ?mz m{ )SM ~ 0:0295z0:0028 {0:0025 Notably, BSM theories with the property of minimal flavour violation16 predict the same value as the SM for this ratio The first evidence for the decay B0s ?mz m{ was presented by the LHCb collaboration in 201217 Both CMS and LHCb later published results from all data collected in proton–proton collisions at centre-ofmass energies of TeV in 2011 and TeV in 2012 The measurements had comparable precision and were in good agreement18,19, although neither of the individual results had sufficient precision to constitute the first definitive observation of the B0s decay to two muons In this Letter, the two sets of data are combined and analysed simultaneously to exploit fully the statistical power of the data and to account for the main correlations between them The data correspond to total integrated luminosities of 25 fb21 and fb21 for the CMS and LHCb experiments, respectively, equivalent to a total of approximately 1012 B0s and B0 mesons produced in the two experiments together Assuming the branching fractions given by the SM and accounting for the detection efficiencies, the predicted numbers of decays to be observed in the two experiments together are about 100 for B0s ?mz m{ and 10 for B0 R m1m2 The CMS20 and LHCb21 detectors are designed to measure SM phenomena with high precision and search for possible deviations The two collaborations use different and complementary strategies In addition to performing a broad range of precision tests of the SM and studying the newly-discovered Higgs boson22,23, CMS is designed to search for and study new particles with masses from about 100 GeV/c2 to a few TeV/c2 Since many of these new particles would be able to decay into b quarks and many of the SM measurements also involve b quarks, the detection of b-hadron decays was a key element in the design of CMS The LHCb collaboration has optimized its detector to study matter–antimatter asymmetries and rare decays of particles containing b quarks, aiming to detect deviations from precise SM predictions that would indicate BSM effects These different approaches, reflected in the design of the detectors, lead to instrumentation of complementary angular regions with respect to the LHC beams, to operation at different proton–proton collision rates, and to selection of b quark events with different efficiency (for experimental details, see Methods) In general, CMS operates at a higher instantaneous luminosity than LHCb but has a lower efficiency for reconstructing low-mass particles, resulting in a similar sensitivity to LHCb for B0 or B0s (denoted hereafter by B0(s) ) mesons decaying into two muons Muons not have strong nuclear interactions and are too massive to emit a substantial fraction of their energy by electromagnetic π+ → μ+ν a μ+ W+ π+ B+ → μ+ν b d ν μ+ B0s → μ+μ– b B0s s W– μ– X+ B0s ν t μ– t s Figure | Feynman diagrams related to the B0s Rm m decay a, p1 meson decay through the charged-current process; b, B1 meson decay through the charged-current process; c, a B0s decay through the direct flavour changing neutral current process, which is forbidden in the SM, as indicated by a large red X0 μ– b μ– s μ+ X+ ν t W– μ– ‘X’; d, e, higher-order flavour changing neutral current processes for the B0s ?mz m{ decay allowed in the SM; and f and g, examples of processes for the same decay in theories extending the SM, where new particles, denoted X0 and X1, can alter the decay rate | N AT U R E | VO L 0 | 0 M O N T H G2015 Z0 W– B0s → μ+μ– B0s W– t W+ s g μ+ b μ+ b B0s s B0s → μ+μ– f μ+ W+ μ+ Z0 B0s ν B0s → μ+μ– d b W+ u e B0s → μ+μ– c b B+ u radiation This gives them the unique ability to penetrate dense materials, such as steel, and register signals in detectors embedded deep within them Both experiments use this characteristic to identify muons The experiments follow similar data analysis strategies Decays compatible with B0(s) ?mz m{ (candidate decays) are found by combining the reconstructed trajectories (tracks) of oppositely charged particles identified as muons The separation between genuine B0(s) ?mz m{ decays and random combinations of two muons (combinatorial background), most often from semi-leptonic decays of two different b hadrons, is achieved using the dimuon invariant mass, mmz m{ , and the established characteristics of B0(s) -meson decays For example, because of their lifetimes of about 1.5 ps and their production at the LHC with momenta between a few GeV/c and ,100 GeV/c, B0(s) mesons travel up to a few centimetres before they decay Therefore, the B0(s) ?mz m{ ‘decay vertex’, from which the muons originate, is required to be displaced with respect to the ‘production vertex’, the point where the two protons collide Furthermore, the negative of the B0(s) candidate’s momentum vector is required to point back to the production vertex These criteria, amongst others that have some ability to distinguish known signal events from background events, are combined into boosted decision trees (BDTs)24–26 A BDT is an ensemble of decision trees each placing different selection requirements on the individual variables to achieve the best discrimination between ‘signal-like’ and ‘background-like’ events Both experiments evaluated many variables for their discriminating power and each chose the best set of about ten to be used in its respective BDT These include variables related to the quality of the reconstructed tracks of the muons; kinematic variables such as transverse momentum (with respect to the beam axis) of the individual muons and of the B0(s) candidate; variables related to the decay vertex topology and fit quality, such as candidate decay length; and isolation variables, which measure the activity in terms of other particles in the vicinity of the two muons or their displaced vertex A BDT must be ‘trained’ on collections of known background and signal events to generate the selection requirements on the variables and the weights for each tree In the case of CMS, the background events used in the training are taken from intervals of dimuon mass above and below the signal region in data, while simulated events are used for the signal The data are divided into disjoint sub-samples and the BDT trained on one sub-sample is applied to a different sub-sample to avoid any bias LHCb uses simulated events for background and signal in the training of its BDT After training, the relevant BDT is applied to each event in the data, returning a single value for the event, with high values being more signal-like To avoid possible biases, both experiments kept the small mass interval that includes both the B0s and B0 signals blind until all selection criteria were established Macmillan Publishers Limited All rights reserved LETTER RESEARCH In addition to the combinatorial background, specific b-hadron decays, such as B0 R p2m1n where the neutrino cannot be detected and the charged pion is misidentified as a muon, or B0 R p0 m1m2, where the neutral pion in the decay is not reconstructed, can mimic the dimuon decay of the B0(s) mesons The invariant mass of the reconstructed dimuon candidate for these processes (semi-leptonic background) is usually smaller than the mass of the B0s or B0 meson because the neutrino or another particle is not detected There is also a background component from hadronic two-body B0(s) decays (peaking background) as B0 R K1 p2, when both hadrons from the decay are misidentified as muons These misidentified decays can produce peaks in the dimuon invariant-mass spectrum near the expected signal, especially for the B0 R m1 m2 decay Particle identification algorithms are used to minimize the probability that pions and kaons are misidentified as muons, and thus suppress these background sources Excellent mass resolution is mandatory for distinguishing between B0 and B0s mesons with a mass difference of about 87 MeV/c2 and for separating them from backgrounds The mass resolution for B0s ?mz m{ decays in CMS ranges from 32 to 75 MeV/c2, depending on the direction of the muons relative to the beam axis, while LHCb achieves a uniform mass resolution of about 25 MeV/c2 The CMS and LHCb data are combined by fitting a common value for each branching fraction to the data from both experiments The branching fractions are determined from the observed numbers, efficiencycorrected, of B0(s) mesons that decay into two muons and the total numbers of B0(s) mesons produced Both experiments derive the latter from the number of observed B1 R J/y K1 decays, whose branching fraction has been precisely measured elsewhere14 Assuming equal rates for B1 and B0 production, this gives the normalization for B0 R m1m2 To derive the number of B0s mesons from this B1 decay mode, the ratio of b quarks that form (hadronize into) B1 mesons to those that form B0s mesons is also needed Measurements of this ratio27,28, for which there is additional discussion in Methods, and of the branching fraction B(B1 R J/y K1) are used to normalize both sets of data and are constrained within Gaussian uncertainties in the fit The use of these two results by both CMS and LHCb is the only significant source of correlation between their individual branching fraction measurements The combined fit takes advantage of the larger data sample to increase the precision while properly accounting for the correlation In the simultaneous fit to both the CMS and LHCb data, the branching fractions of the two signal channels are common parameters of interest and are free to vary Other parameters in the fit are considered as nuisance parameters Those for which additional knowledge is available are constrained to be near their estimated values by using Gaussian penalties with their estimated uncertainties while the others are free to float in the fit The ratio of the hadronization probability into B1 and B0s mesons and the branching fraction of the normalization channel B1 R J/y K1 are common, constrained parameters Candidate decays are categorized according to whether they were detected in CMS or LHCb and to the value of the relevant BDT discriminant In the case of CMS, they are further categorized according to the data-taking period, and, because of the large variation in mass resolution with angle, whether the muons are both produced at large angles relative to the proton beams (central-region) or at least one muon is emitted at small angle relative to the beams (forward-region) An unbinned extended maximum likelihood fit to the dimuon invariant-mass distribution, in a region of about 6500 MeV/c2 around the B0s mass, is performed simultaneously in all categories (12 categories from CMS and eight from LHCb) Likelihood contours in the plane of the parameters of interest, B(B0 R m1m2) versus B(B0s ?mz m{ ), are obtained by constructing the test statistic 22DlnL from the difference in log-likelihood (lnL) values between fits with fixed values for the parameters of interest and the nominal fit For each of the two branching fractions, a one-dimensional profile likelihood scan is likewise obtained by fixing only the single parameter of interest and allowing the other to vary during the fits Additional fits are performed where the parameters under consideration are the ratio of the branching B0 (s) :B(B0(s) ?mz m{ )= fractions relative to their SM predictions, S SM B(B0(s) ?mz m{ )SM , or the ratio R of the two branching fractions The combined fit result is shown for all 20 categories in Extended Data Fig To represent the result of the fit in a single dimuon invariant-mass spectrum, the mass distributions of all categories, weighted according to values of S/(S B), where S is the expected number of B0s signals and B is the number of background events under the B0s peak in that category, are added together and shown in Fig The result of the simultaneous fit is overlaid An alternative representation of the fit to the dimuon invariant-mass distribution for the six CMS and LHCb (LHC run I) 60 Data Weighted candidates per 40 MeV/c2 Signal and background Bs → μ+μ– 50 B0 → μ+μ– Combinatorial background 40 Semi-leptonic background Peaking background 30 20 10 5,000 5,200 5,400 mμ+μ– (MeV/c2) Figure | Weighted distribution of the dimuon invariant mass, mm1m2, for all categories Superimposed on the data points in black are the combined fit (solid blue line) and its components: the B0s (yellow shaded area) and B0 (lightblue shaded area) signal components; the combinatorial background (dashdotted green line); the sum of the semi-leptonic backgrounds (dotted salmon 5,600 5,800 line); and the peaking backgrounds (dashed violet line) The horizontal bar on each histogram point denotes the size of the binning, while the vertical bar denotes the 68% confidence interval See main text for details on the weighting procedure 0 M O N T H | VO L 0 | N AT U R E | G2015 Macmillan Publishers Limited All rights reserved RESEARCH LETTER CMS and LHCb (LHC run I) a 0.9 b –2ΔlnL –9 ×10 5.7 –7 ×10 10 c 0.3 –2ΔlnL SM 0.1 (B0s → μ+μ–) (10−9) 10 SM 0.2 20 –5 5% 7% 0.4 6.3 95.4 68.2 0.5 3% 99.7 0.6 30 10 2× 1− 1− 0.7 (B0 → μ+μ–) (10−9) SM 1− 0.8 40 2 (B0s → μ+μ–) 0 0.2 0.4 0.6 0.8 (B0 → μ+μ–) (10−9) (10−9) Figure | Likelihood contours in the B(B0 R m1m2) versus B(Bs0 Rm1m2) plane The (black) cross in a marks the best-fit central value The SM expectation and its uncertainty is shown as the (red) marker Each contour encloses a region approximately corresponding to the reported confidence level b, c, Variations of the test statistic 22DlnL for B(B0s ?mz m{ ) (b) and B(B0 R m1m2) (c) The dark and light (cyan) areas define the 61s and 62s confidence intervals for the branching fraction, respectively The SM prediction and its uncertainty for each branching fraction is denoted with the vertical (red) band categories with the highest S/(S B) value for CMS and LHCb, as well as displays of events with high probability to be genuine signal decays, are shown in Extended Data Figs 2–4 The combined fit leads to the measurements B(B0s ?mz m{ )~ {9 {10 (2:8z0:7 and B(B0 ?mz m{ )~(3:9z1:6 , where the {1:4 )|10 {0:6 ) |10 uncertainties include both statistical and systematic sources, the latter contributing 35% and 18% of the total uncertainty for the B0s and B0 signals, respectively Using Wilks’ theorem29, the statistical significance in unit of standard deviations, s, is computed to be 6.2 for the B0s ?mz m{ decay mode and 3.2 for the B0 R m1m2 mode For each signal the null hypothesis that is used to compute the significance includes all background components predicted by the SM as well as the other signal, whose branching fraction is allowed to vary freely The median expected significances assuming the SM branching fractions are 7.4s and 0.8s for the B0s and B0 modes, respectively Likelihood contours for B(B0 R m1m2) versus B(B0s ?mz m{ ) are shown in Fig One-dimensional likelihood scans for both decay modes are displayed in the same figure In addition to the likelihood scan, the statistical significance and confidence intervals for the B0 branching fraction are determined using simulated experiments This determination yields a significance of 3.0s for a B0 signal with respect to the same null hypothesis described above Following the Feldman–Cousins30 procedure, 61s and 62s confidence intervals for B(B0 R m1m2) of [2.5, 5.6] 10210 and [1.4, 7.4] 10210 are obtained, respectively (see Extended Data Fig 5) The fit for the ratios of the branching fractions relative to their SM B0s B0 z1:6 predictions yields S SM ~0:76z0:20 and S ~3:7 SM {0:18 {1:4 Associated likelihood contours and one-dimensional likelihood scans are shown in Extended Data Fig The measurements are compatible with the SM branching fractions of the B0s ?mz m{ and B0 R m1m2 decays at the 1.2s and 2.2s level, respectively, when computed from the onedimensional hypothesis tests Finally, the fit for the ratio of branching z0:08 fractions yields R~0:14{0:06, which is compatible with the SM at the 2.3s level The one-dimensional likelihood scan for this parameter is shown in Fig The combined analysis of data from CMS and LHCb, taking advantage of their full statistical power, establishes conclusively the existence of the B0s ?mz m{ decay and provides an improved measurement of its branching fraction This concludes a search that started more than three decades ago (see Extended Data Fig 7), and initiates a phase of precision measurements of the properties of this decay It also produces three standard deviation evidence for the B0 R m1m2 decay The measured branching fractions of both decays are compatible with SM predictions This is the first time that the CMS and LHCb collaborations have performed a combined analysis of sets of their data in order to obtain a statistically significant observation CMS and LHCb (LHC run I) Online Content Methods, along with any additional Extended Data display items and Source Data, are available in the online version of the paper; references unique to these sections appear only in the online paper 10 SM and MFV Received 12 November 2014; accepted 31 March 2015 –2ΔlnL Published online 13 May 2015 4 0 0.1 0.2 0.3 0.4 0.5 Figure | Variation of the test statistic 22DlnL as a function of the ratio of branching fractions R:B(B0 Rm1m2)/B(Bs0 Rm1m2) The dark and light (cyan) areas define the 61s and 62s confidence intervals for R, respectively The value and uncertainty for R predicted in the SM, which is the same in BSM theories with the minimal flavour violation (MFV) property, is denoted with the vertical (red) band 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dependence on B meson kinematics J High Energy Phys 4, (2013); updated in https://cds.cern.ch/record/1559262/files/LHCb-CONF-2013011.pdf Wilks, S S The large-sample distribution of the likelihood ratio for testing composite hypotheses Ann Math Stat 9, 60–62 (1938) Feldman, G J & Cousins, R D Unified approach to the classical statistical analysis of small signals Phys Rev D 57, 3873–3889 (1998) Acknowledgements We express our gratitude to colleagues in the CERN accelerator departments for the excellent performance of the LHC We thank the technical and administrative staff at CERN, at the CMS institutes and at the LHCb institutes In addition, we gratefully acknowledge the computing centres and personnel of the Worldwide LHC Computing Grid for delivering so effectively the computing infrastructure essential to our analyses Finally, we acknowledge the enduring support for the construction and operation of the LHC, the CMS and the LHCb detectors provided by CERN and by many funding agencies The following agencies provide support for both CMS and LHCb: CAPES, CNPq, FAPERJ and FINEP (Brazil); NSFC (China); CNRS/IN2P3 (France); BMBF, DFG and HGF (Germany); SFI (Ireland); INFN (Italy); NASU (Ukraine); STFC (UK); and NSF (USA) Agencies that provide support for CMS only are BMWFW and FWF (Austria); FNRS and FWO (Belgium); FAPESP (Brazil); MES (Bulgaria); CAS and MoST (China); COLCIENCIAS (Colombia); MSES and CSF (Croatia); RPF (Cyprus); MoER, ERC IUT and ERDF (Estonia); Academy of Finland, MEC, and HIP (Finland); CEA (France); GSRT (Greece); OTKA and NIH (Hungary); DAE and DST (India); IPM (Iran); NRF and WCU (Republic of Korea); LAS (Lithuania); MOE and UM (Malaysia); CINVESTAV, CONACYT, SEP, and UASLP-FAI (Mexico); MBIE (New Zealand); PAEC (Pakistan); MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna); MON, RosAtom, RAS and RFBR (Russia); MESTD (Serbia); SEIDI and CPAN (Spain); Swiss Funding Agencies (Switzerland); MST (Taipei); ThEPCenter, IPST, STAR and NSTDA (Thailand); TUBITAK and TAEK (Turkey); SFFR (Ukraine); and DOE (USA) Agencies that provide support for only LHCb are: FINEP (Brazil); MPG (Germany); FOM and NWO (The Netherlands); MNiSW and NCN (Poland); MEN/IFA (Romania); MinES and FANO (Russia); MinECo (Spain); SNSF and SER (Switzerland) Individuals from the CMS collaboration have received support from the Marie-Curie programme and the European Research Council and EPLANET (European Union); the Leventis Foundation; the A P Sloan Foundation; the Alexander von Humboldt Foundation; the Belgian Federal Science Policy Office; the Fonds pour la Formation a` la Recherche dans l’Industrie et dans l’Agriculture (FRIABelgium); the Agentschap voor Innovatie door Wetenschap en Technologie (IWT-Belgium); the Ministry of Education, Youth and Sports (MEYS) of the Czech Republic; the Council of Science and Industrial Research, India; the HOMING PLUS programme of Foundation for Polish Science, cofinanced from European Union, Regional Development Fund; the Compagnia di San Paolo (Torino); the Consorzio per la Fisica (Trieste); MIUR project 20108T4XTM (Italy); the Thalis and Aristeia programmes cofinanced by EU-ESF and the Greek NSRF; and the National Priorities Research Program by Qatar National Research Fund Individual groups or members of the LHCb collaboration have received support from EPLANET, Marie Skłodowska-Curie Actions and ERC (European Union), Conseil ge´ne´ral de Haute-Savoie, Labex ENIGMASS and OCEVU, Re´gion Auvergne (France), RFBR (Russia), XuntaGal and GENCAT (Spain), Royal Society and Royal Commission for the Exhibition of 1851 (UK) LHCb is also thankful for the computing resources and the access to software R&D tools provided by Yandex LLC (Russia) The CMS and LHCb collaborations are indebted to the communities behind the multiple open source software packages on which they depend Author Contributions All authors have contributed to the publication, being variously involved in the design and the construction of the detectors, in writing software, calibrating sub-systems, operating the detectors and acquiring data and finally analysing the processed data Author Information Reprints and permissions information is available at www.nature.com/reprints The authors declare no competing financial interests Readers are welcome to comment on the online version of the paper Correspondence and requests for materials should be addressed to cms-publication-committee-chair@cern.ch and to lhcb-editorial-board-chair@cern.ch This work is licensed under a Creative Commons AttributionNonCommercial-ShareAlike 3.0 Unported licence The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons licence, users will need to obtain permission from the licence holder to reproduce the material To view a copy of this licence, visit http://creativecommons org/licenses/by-nc-sa/3.0 0 M O N T H | VO L 0 | N AT U R E | G2015 Macmillan Publishers Limited All rights reserved RESEARCH LETTER METHODS Experimental setup At the Large Hadron Collider (LHC), two counter-rotating beams of protons, contained and guided by superconducting magnets spaced around a 27 km circular tunnel, located approximately 100 m underground near Geneva, Switzerland, are brought into collision at four interaction points (IPs) The study presented in this Letter uses data collected at energies of 3.5 TeV per beam in 2011 and TeV per beam in 2012 by the CMS and LHCb experiments located at two of these IPs The CMS and LHCb detectors are both designed to look for phenomena beyond the SM (BSM), but using complementary strategies The CMS detector20, shown in Extended Data Fig 3, is optimized to search for yet unknown heavy particles, with masses ranging from 100 GeV/c2 to a few TeV/c2, which, if observed, would be a direct manifestation of BSM phenomena Since many of the hypothesized new particles can decay into particles containing b quarks or into muons, CMS is able to detect efficiently and study B0 (5,280 MeV/c2) and B0s (5,367 MeV/c2) mesons decaying to two muons even though it is designed to search for particles with much larger masses The CMS detector covers a very large range of angles and momenta to reconstruct high-mass states efficiently To that extent, it employs a 13 m long, m diameter superconducting solenoid magnet, operated at a field of 3.8 T, centred on the IP with its axis along the beam direction and covering both hemispheres A series of silicon tracking layers, consisting of silicon pixel detectors near the beam and silicon strips farther out, organized in concentric cylinders around the beam, extending to a radius of 1.1 m and terminated on each end by planar detectors (disks) perpendicular to the beam, measures the momentum, angles, and position of charged particles emerging from the collisions Tracking coverage starts from the direction perpendicular to the beam and extends to within 220 mrad from it on both sides of the IP The inner three cylinders and disks extending from 4.3 to 10.7 cm in radius transverse to the beam are arrays of 100 150 mm2 silicon pixels, which can distinguish the displacement of the b-hadron decays from the primary vertex of the collision The silicon strips, covering radii from 25 cm to approximately 110 cm, have pitches ranging from 80 to 183 mm The impact parameter is measured with a precision of 10 mm for transverse momenta of 100 GeV/c and 20 mm for 10 GeV/c The momentum resolution, provided mainly by the silicon strips, changes with the angle relative to the beam direction, resulting in a mass resolution for B0(s) ?mz m{ decays that varies from 32 MeV/c2 for B0(s) mesons produced perpendicularly to the proton beams to 75 MeV/c2 for those produced at small angles relative to the beam direction After the tracking system, at a greater distance from the IP, there is a calorimeter that stops (absorbs) all particles except muons and measures their energies The calorimeter consists of an electromagnetic section followed by a hadronic section Muons are identified by their ability to penetrate the calorimeter and the steel return yoke of the solenoid magnet and to produce signals in gas-ionization particle detectors located in compartments within the steel yoke The CMS detector has no capability to discriminate between charged hadron species, pions, kaons, or protons, that is effective at the typical particle momenta in this analysis The primary commitment of the LHCb collaboration is the study of particle– antiparticle asymmetries and of rare decays of particles containing b and c quarks LHCb aims at detecting BSM particles indirectly by measuring their effect on b-hadron properties for which precise SM predictions exist The production cross section of b hadrons at the LHC is particularly large at small angles relative to the colliding beams The small-angle region also provides advantages for the detection and reconstruction of a wide range of their decays The LHCb experiment21, shown in Extended Data Fig 4, instruments the angular interval from 10 to 300 mrad with respect to the beam direction on one side of the interaction region Its detectors are designed to reconstruct efficiently a wide range of b-hadron decays, resulting in charged pions and kaons, protons, muons, electrons, and photons in the final state The detector includes a high-precision tracking system consisting of a silicon strip vertex detector, a large-area silicon strip detector located upstream of a dipole magnet characterized by a field integral of T m, and three stations of silicon strip detectors and straw drift tubes downstream of the magnet The vertex detector has sufficient spatial resolution to distinguish the slight displacement of the weakly decaying b hadron from the primary production vertex where the two protons collided and produced it The tracking detectors upstream and downstream of the dipole magnet measure the momenta of charged particles The combined tracking system provides a momentum measurement with an uncertainty that varies from 0.4% at GeV/c to 0.6% at 100 GeV/c This results in an invariant-mass resolution of 25 MeV/c2 for B0(s) mesons decaying to two muons that is nearly independent of the angle with respect to the beam The impact parameter resolution is smaller than 20 mm for particle tracks with large transverse momentum Different types of charged hadrons are distinguished by information from two ring-imaging Cherenkov detectors Photon, electron, and hadron candidates are identified by calorimeters Muons are identified by a system composed of alternating layers of iron and multiwire proportional chambers G2015 Neither CMS nor LHCb records all the interactions occurring at its IP because the data storage and analysis costs would be prohibitive Since most of the interactions are reasonably well characterized (and can be further studied by recording only a small sample of them) specific event filters (known as triggers) select the rare processes that are of interest to the experiments Both CMS and LHCb implement triggers that specifically select events containing two muons The triggers of both experiments have a hardware stage, based on information from the calorimeter and muon systems, followed by a software stage, consisting of a large computing cluster that uses all the information from the detector, including the tracking, to make the final selection of events to be recorded for subsequent analysis Since CMS is designed to look for much heavier objects than B0(s) mesons, it selects events that contain muons with higher transverse momenta than those selected by LHCb This eliminates many of the B0(s) decays while permitting CMS to run at a higher proton–proton collision rate to look for the more rare massive particles Thus CMS runs at higher collision rates but with lower efficiency than LHCb for B0ðsÞ mesons decaying to two muons The overall sensitivity to these decays turns out to be similar in the two experiments CMS and LHCb are not the only collaborations to have searched for B0s ?mz m{ and B0R m1 m2 decays Over three decades, a total of eleven collaborations have taken part in this search14, as illustrated by Extended Data Fig This plot gathers the results from CLEO31–35, ARGUS36, UA137,38, CDF39–44, L345, DØ46–50, Belle51, Babar52,53, LHCb17,54–57 CMS18,58,59 and ATLAS60 Analysis description The analysis techniques used to obtain the results presented in this Letter are very similar to those used to obtain the individual result in each collaboration, described in more detail in refs 18, 19 Here only the main analysis steps are reviewed and the changes used in the combined analysis are highlighted Data samples for this analysis were collected by the two experiments in proton– proton collisions at a centre-of-mass energy of and TeV during 2011 and 2012, respectively These samples correspond to a total integrated luminosity of 25 and fb21 for the CMS and LHCb experiments, respectively, and represent their complete data sets from the first running period of the LHC The trigger criteria were slightly different between the two experiments The large majority of events were triggered by requirements on one or both muons of the signal decay: the LHCb detector triggered on muons with transverse momentum pT 1.5 GeV/c while the CMS detector, because of its geometry and higher instantaneous luminosity, triggered on two muons with pT (3) GeV/c, for the leading (sub-leading) muon The data analysis procedures in the two experiments follow similar strategies Pairs of high-quality oppositely charged particle tracks that have one of the expected patterns of hits in the muon detectors are fitted to form a common vertex in three dimensions, which is required to be displaced from the primary interaction vertex (PV) and to have a small x2 in the fit The resulting B0(s) candidate is further required to point back to the PV, for example, to have a small impact parameter, consistent with zero, with respect to it The final classification of data events is done in categories of the response of a multivariate discriminant (MVA) combining information from the kinematics and vertex topology of the events The type of MVA used is a boosted decision tree (BDT)24–26 The branching fractions are then obtained by a fit to the dimuon invariant mass, mmz m{ , of all categories simultaneously The signals appear as peaks at the B0s and B0 masses in the invariant-mass distributions, observed over background events One of the components of the background is combinatorial in nature, as it is due to the random combinations of genuine muons These produce a smooth dimuon mass distribution in the vicinity of the B0s and B0 masses, estimated in the fit to the data by extrapolation from the sidebands of the invariant-mass distribution In addition to the combinatorial background, certain specific b-hadron decays can mimic the signal or contribute to the background in its vicinity In particular, the semi-leptonic decays B0 R p2m1n, B0s R K2m1n, and L0b ?pm{n can have reconstructed masses that are near the signal if one of the hadrons is misidentified as a muon and is combined with a genuine muon Similarly the dimuon coming from the rare B0 R p0m1m2 and B1 R p1m1m2 decays can also fake the signal All these background decays, when reconstructed as a dimuon final state, have invariant masses that are lower than the masses of the B0 and B0s mesons, because they are missing one of the original decay particles An exception is the decay L0b ?pm{n, which can also populate, with a smooth mass distribution, higher-mass regions Furthermore, background due to misidentified hadronic two-body decays B0(s) ?hz h’{ , where h(0) ~p or K, is present when both hadrons are misidentified as muons These misidentified decays produce an apparent dimuon invariant-mass peak close to the B0 mass value Such a peak can mimic a B0 R m1m2 signal and is estimated from control channels and added to the fit The distributions of signal in the invariant mass and in the MVA discriminant are derived from simulations with a detailed description of the detector response Macmillan Publishers Limited All rights reserved LETTER RESEARCH for CMS and are calibrated using exclusive two-body hadronic decays in data for LHCb The distributions for the backgrounds are obtained from simulation with the exception of the combinatorial background The latter is obtained by interpolating from the data invariant-mass sidebands separately for each category, after the subtraction of the other background components To compute the signal branching fractions, the numbers of B0s and B0 mesons that are produced, as well as the numbers of those that have decayed into a dimuon pair, are needed The latter numbers are the raw results of this analysis, whereas the former need to be determined from measurements of one or more ‘normalization’ decay channels, which are abundantly produced, have an absolute branching fraction that is already known with good precision, and that share characteristics with the signals, so that their trigger and selection efficiencies not differ significantly Both experiments use the B1 R J/y K1 decay as a normalization channel with B(B1 R J/y (m1m2) K1) (6.10 0.19) 1025, and LHCb also uses the B0 R K1p2 channel with B(B0 R K1p2) (1.96 0.05) 1025 Both branching fraction values are taken from ref 14 Hence, the B0s R m1m2 branching fraction is expressed as a function of the number of signal events (NB0s ?mz m{ ) in the data normalized to the numbers of B1 R J/y K1 and B0 R K1p2 events: NB0 ?mz m{ fd enorm: | | |Bnorm: ~anorm: |NB0s ?mz m{ ð1Þ B(B0s ?mz m{ )~ s Nnorm: fs eB0s ?mz m{ where the ‘norm.’ subscript refers to either of the normalization channels The values of the normalization parameter anorm obtained by LHCb from the two normalization channels are found in good agreement and their weighted average is used In this formula e indicates the total event detection efficiency including geometrical acceptance, trigger selection, reconstruction, and analysis selection for the corresponding decay The fd/fs factor is the ratio of the probabilities for a b quark to hadronize into a B0 as compared to a B0s meson; the probability to hadronize into a B1 (fu) is assumed to be equal to that into B0 (fd) on the basis of theoretical grounds, and this assumption is checked on data The value of fd/fs 3.86 0.22 measured by LHCb27,28,61 is used in this analysis As the value of fd/fs depends on the kinematic range of the considered particles, which differs between LHCb and CMS, CMS checked this observable with the decays B0s ?J=yw and B1 R J/yK1 within its acceptance, finding a consistent value An additional systematic uncertainty of 5% was assigned to fd/fs to account for the extrapolation of the LHCb result to the CMS acceptance An analogous formula to that in equation (1) holds for the normalization of the B0 R m1m2 decay, with the notable difference that the fd/fs factor is replaced by fd/fu  0s ) and the particle B0 (B0s ) can both decay into two muons  (B The antiparticle B and no attempt is made in this analysis to determine whether the antiparticle or particle was produced (untagged method) However, the B0 and B0s particles are known to oscillate, that is to transform continuously into their antiparticles and vice versa Therefore, a quantum superposition of particle and antiparticle states propagates in the laboratory before decaying This superposition can be described by two ‘mass eigenstates’, which are symmetric and antisymmetric in the chargeparity (CP) quantum number, and have slightly different masses In the SM, the heavy eigenstate can decay into two muons, whereas the light eigenstate cannot without violating the CP quantum number conservation In BSM models, this is not necessarily the case In addition to their masses, the two eigenstates of the B0s system also differ in their lifetime values14 The lifetimes of the light and heavy eigenstates are also different from the average B0s lifetime, which is used by CMS and LHCb in the simulations of signal decays Since the information on the displacement of the secondary decay with respect to the PV is used as a discriminant against combinatorial background in the analysis, the efficiency versus lifetime has a model-dependent bias62 that must be removed This bias is estimated assuming SM dynamics Owing to the smaller difference between the lifetime of its heavy and light mass eigenstates, no correction is required for the B0 decay mode Detector simulations are needed by both CMS and LHCb CMS relies on simulated events to determine resolutions and trigger and reconstruction efficiencies, and to provide the signal sample for training the BDT The dimuon mass resolution given by the simulation is validated using data on J/y, U, and Z-boson decays to two muons The tracking and trigger efficiencies obtained from the simulation are checked using special control samples from data The LHCb analysis is designed to minimize the impact of discrepancies between simulations and data The mass resolution is measured with data The distribution of the BDT for the signal and for the background is also calibrated with data using control channels and mass sidebands The efficiency ratio for the trigger is also largely determined from data The simulations are used to determine the efficiency ratios of selection and reconstruction processes between signal and normalization channels As for the overall detector simulation, each experiment has a team dedicated to making the simulations as complete and realistic as possible The simulated data are constantly being compared to the G2015 actual data Agreement between simulation and data in both experiments is quite good, often extending well beyond the cores of distributions Differences occur because, for example, of incomplete description of the material of the detectors, approximations made to keep the computer time manageable, residual uncertainties in calibration and alignment, and discrepancies or limitations in the underlying theory and experimental data used to model the relevant collisions and decays Small differences between simulation and data that are known to have an impact on the result are treated either by reweighting the simulations to match the data or by assigning appropriate systematic uncertainties Small changes are made to the analysis procedure with respect to refs 18, 19 in order to achieve a consistent combination between the two experiments In the LHCb analysis, the L0b ?pm{ n background component, which was not included in the fit for the previous result but whose effect was accounted for as an additional systematic uncertainty, is now included in the standard fit The following modifications are made to the CMS analysis: the L0b ?pm{n branching fraction is updated to a more recent prediction63,64 of B(L0b ?pm{n)~(4:94+2:19) |10{4 ; the phase space model of the decay L0b ?pm{ n is changed to a more appropriate semileptonic decay model63; and the decay time bias correction for the B0s, previously absent from the analysis, is now calculated and applied with a different correction for each category of the multivariate discriminant These modifications result in changes in the individual results of each experiment The modified CMS analysis, applied on the CMS data, yields {9 {10 and B(B0 ?mz m{ )~(4:4z2:2 ð2Þ B(B0s ?mz m{ )~(2:8z1:1 {0:9 )|10 {1:9 )|10 while the LHCb results change to {9 {10 B(B0s ?mz m{ )~(2:7z1:1 and B(B0 ?mz m{ )~(3:3z2:4 ð3Þ {0:9 )|10 {2:1 )|10 These results are only slightly different from the published ones and are in agreement with each other Simultaneous fit The goal of the analysis presented in this Letter is to combine the full data sets of the two experiments to reduce the uncertainties on the branching fractions of the signal decays obtained from the individual determinations A simultaneous unbinned extended maximum likelihood fit is performed to the data of the two experiments, using the invariant-mass distributions of all 20 MVA discriminant categories of both experiments The invariant-mass distributions are defined in the dimuon mass ranges mmz m{ g[4.9, 5.9] GeV/c2 and [4.9, 6.0] GeV/c2 for the CMS and LHCb experiments, respectively The branching fractions of the signal decays, the hadronization fraction ratio fd/fs, and the branching fraction of the normalization channel B1 R J/y K1 are treated as common parameters The value of the B1 R J/y K1 branching fraction is the combination of results from five different experiments14, taking advantage of all their data to achieve the most precise input parameters for this analysis The combined fit takes advantage of the larger data sample and proper treatment of the correlations between the individual measurements to increase the precision and reliability of the result, respectively Fit parameters, other than those of primary physics interest, whose limited knowledge affects the results, are called ‘nuisance parameters’ In particular, systematic uncertainties are modelled by introducing nuisance parameters into the statistical model and allowing them to vary in the fit; those for which additional knowledge is present are constrained using Gaussian distributions The mean and standard deviation of these distributions are set to the central value and uncertainty obtained either from other measurements or from control channels The statistical component of the final uncertainty on the branching fractions is obtained by repeating the fit after fixing all of the constrained nuisance parameters to their best fitted values The systematic component is then calculated by subtracting in quadrature the statistical component from the total uncertainty In addition to the free fit, a two-dimensional likelihood ratio scan in the plane B(B0 R m1m2) versus B(B0s ?mz m{ ) is performed Feldman–Cousins confidence interval The Feldman–Cousins likelihood ratio ordering procedure30 is a unified frequentist method to construct single- and double-sided confidence intervals for parameters of a given model adapted to the data It provides a natural transition between single-sided confidence intervals, used to define upper or lower limits, and double-sided ones Since the singleexperiment results18,19 showed that the B0 R m1m2 signal is at the edge of the probability region customarily used to assert statistically significant evidence for a result, a Feldman–Cousins procedure is performed This allows a more reliable determination of the confidence interval and significance of this signal without the assumptions required for the use of Wilks’ theorem In addition, a prescription for the treatment of nuisance parameters has to be chosen because scanning the whole parameter space in the presence of more than a few parameters is computationally too intensive In this case the procedure described by the ATLAS and CMS Higgs combination group65 is adopted For each point of the space of the relevant parameters, the nuisance parameters are fixed to their best value estimated by the mean Macmillan Publishers Limited All rights reserved RESEARCH LETTER of a maximum likelihood fit to the data with the value of B(B0 R m1m2) fixed and all nuisance parameters profiled with Gaussian penalties Sampling distributions are constructed for each tested point of the parameter of interest by generating simulated experiments and performing maximum likelihood fits in which the Gaussian mean values of the external constraints on the nuisance parameters are randomized around the best-fit values for the nuisance parameters used to generate the simulated experiments The sampling distribution is constructed from the distribution of the negative log-likelihood ratio evaluated on the simulated experiments by performing one likelihood fit 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Procedure for the LHC Higgs boson search combination in summer 2011 http://cds.cern.ch/record/1379837 (ATL-PHYSPUB-2011-011, CMS NOTE 2011/005, 2011) Macmillan Publishers Limited All rights reserved LETTER RESEARCH CMS Collaboration V Khachatryan1, A.M Sirunyan1, A Tumasyan1, W Adam2, T Bergauer2, M Dragicevic2, J Eroă2, M Friedl2, R Fruăhwirth2,204, V.M Ghete2, C Hartl2, N Hoărmann2, J Hrubec2, M Jeitler2,204, W Kiesenhofer2, V Knuănz2, M Krammer2,204, I Kraătschmer2, D Liko2, I Mikulec2, D Rabady2,205, B Rahbaran2, H Rohringer2, R Schoăfbeck2, J Strauss2, W Treberer-Treberspurg2, W Waltenberger2, C.-E Wulz2,204, V Mossolov3, N Shumeiko3, J Suarez Gonzalez3, S Alderweireldt4, S Bansal4, T Cornelis4, E.A De Wolf4, X Janssen4, A Knutsson4, J Lauwers4, S Luyckx4, S Ochesanu4, R Rougny4, M Van De Klundert4, H Van Haevermaet4, P Van Mechelen4, N Van Remortel4, A Van Spilbeeck4, F Blekman5, S Blyweert5, J D’Hondt5, N Daci5, N Heracleous5, J Keaveney5, S Lowette5, M Maes5, A Olbrechts5, Q Python5, D Strom5, S Tavernier5, W Van Doninck5, P Van Mulders5, G.P Van Onsem5, I Villella5, C Caillol6, B Clerbaux6, G De Lentdecker6, D Dobur6, L Favart6, A.P.R Gay6, A Grebenyuk6, A Le´onard6, A Mohammadi6, L Pernie`6,205, A Randle-conde6, T Reis6, T Seva6, L Thomas6, C Vander Velde6, P Vanlaer6, J Wang6, F Zenoni6, V Adler7, K Beernaert7, L Benucci7, A Cimmino7, S Costantini7, S Crucy7, S Dildick7, A Fagot7, G Garcia7, J Mccartin7, A.A Ocampo Rios7, D Ryckbosch7, S Salva Diblen7, M Sigamani7, N Strobbe7, F Thyssen7, M Tytgat7, E Yazgan7, N Zaganidis7, S Basegmez8, C Beluffi8,206, G Bruno8, R Castello8, A Caudron8, L Ceard8, G.G Da Silveira8, C Delaere8, T du Pree8, D Favart8, L Forthomme8, A Giammanco8,207, J Hollar8, A Jafari8, P Jez8, M Komm8, V Lemaitre8, C Nuttens8, D Pagano8, L Perrini8, A Pin8, K Piotrzkowski8, A Popov8,208, L Quertenmont8, M Selvaggi8, M Vidal Marono8, J.M Vizan Garcia8, N Beliy9, T Caebergs9, E Daubie9, G.H Hammad9, W.L Alda´ Ju´nior10, G.A Alves10, L Brito10, M Correa Martins Junior10, T Dos Reis Martins10, C Mora Herrera10, M.E Pol10, P Rebello Teles10, W Carvalho11, J Chinellato11,209, A Custo´dio11, E.M Da Costa11, D De Jesus Damiao11, C De Oliveira Martins11, S Fonseca De Souza11, H Malbouisson11, D Matos Figueiredo11, L Mundim11, H Nogima11, W.L Prado Da Silva11, J Santaolalla11, A Santoro11, A Sznajder11, E.J Tonelli Manganote11,209, A Vilela Pereira11, C.A Bernardes14, S Dogra13, T.R Fernandez Perez Tomei13, E.M Gregores14, P.G Mercadante14, S.F Novaes13, Sandra S Padula13, A Aleksandrov15, V Genchev15,205, R Hadjiiska15, P Iaydjiev15, A Marinov15, S Piperov15, M Rodozov15, G Sultanov15, M Vutova15, A Dimitrov16, I Glushkov16, L Litov16, B Pavlov16, P Petkov16, J.G Bian17, G.M Chen17, H.S Chen17, M Chen17, T Cheng17, R Du17, C.H Jiang17, R Plestina17,210, F Romeo17, J Tao17, Z Wang17, C Asawatangtrakuldee18, Y Ban18, Q Li18, S Liu18, Y Mao18, S.J Qian18, D Wang18, Z Xu18, W Zou18, C Avila19, A Cabrera19, L.F Chaparro Sierra19, C Florez19, J.P Gomez19, B Gomez Moreno19, J.C Sanabria19, N Godinovic20, D Lelas20, D Polic20, I Puljak20, Z Antunovic21, M Kovac21, V Brigljevic22, K Kadija22, J Luetic22, D Mekterovic22, L Sudic22, A Attikis23, G Mavromanolakis23, J Mousa23, C Nicolaou23, F Ptochos23, P.A Razis23, M Bodlak24, M Finger24, M Finger Jr.24,211, Y Assran25,212, A Ellithi Kamel25,213, M.A Mahmoud25,214, A Radi25,215,216, M Kadastik26, M Murumaa26, M Raidal26, A Tiko26, P Eerola27, G Fedi27, M Voutilainen27, J Haărkoănen28, V Karimaăki28, R Kinnunen28, M.J Kortelainen28, T Lampe´n28, K LassilaPerini28, S Lehti28, T Linden28, P Luukka28, T Maăenpaăaă28, T Peltola28, E Tuominen28, J Tuominiemi28, E Tuovinen28, L Wendland28, J Talvitie29, T Tuuva29, M Besancon30, F Couderc30, M Dejardin30, D Denegri30, B Fabbro30, J.L Faure30, C Favaro30, F Ferri30, S Ganjour30, A Givernaud30, P Gras30, G Hamel de Monchenault30, P Jarry30, E Locci30, J Malcles30, J Rander30, A Rosowsky30, M Titov30, S Baffioni31, F Beaudette31, P Busson31, C Charlot31, T Dahms31, M Dalchenko31, L Dobrzynski31, N Filipovic31, A Florent31, R Granier de Cassagnac31, L Mastrolorenzo31, P Mine´31, C Mironov31, I.N Naranjo31, M Nguyen31, C Ochando31, G Ortona31, P Paganini31, S Regnard31, R Salerno31, J.B Sauvan31, Y Sirois31, C Veelken31, Y Yilmaz31, A Zabi31, J.-L Agram32,217, J Andrea32, A Aubin32, D Bloch32, J.-M Brom32, E.C Chabert32, C Collard32, E Conte32,217, J.-C Fontaine32,217, D Gele´32, U Goerlach32, C Goetzmann32, A.-C Le Bihan32, K Skovpen32, P Van Hove32, S Gadrat33, S Beauceron34, N Beaupere34, G Boudoul34,205, E Bouvier34, S Brochet34, C.A Carrillo Montoya34, J Chasserat34, R Chierici34, D Contardo34,205, P Depasse34, H El Mamouni34, J Fan34, J Fay34, S Gascon34, M Gouzevitch34, B Ille34, T Kurca34, M Lethuillier34, L Mirabito34, S Perries34, J.D Ruiz Alvarez34, D Sabes34, L Sgandurra34, V Sordini34, M Vander Donckt34, P Verdier34, S Viret34, H Xiao34, Z Tsamalaidze35,211, C Autermann36, S Beranek36, M Bontenackels36, M Edelhoff36, L Feld36, A Heister36, O Hindrichs36, K Klein36, A Ostapchuk36, F Raupach36, J Sammet36, S Schael36, J.F Schulte36, H Weber36, B Wittmer36, V Zhukov36,208, M Ata37, M Brodski37, E Dietz-Laursonn37, D Duchardt37, M Erdmann37, R Fischer37, A Guăth37, T Hebbeker37, C Heidemann37, K Hoepfner37, D Klingebiel37, S Knutzen37, P Kreuzer37, M Merschmeyer37, A Meyer37, P Millet37, M Olschewski37, K Padeken37, P Papacz37, H Reithler37, S.A Schmitz37, L Sonnenschein37, D Teyssier37, S Thuăer37, M Weber37, V Cherepanov38, Y Erdogan38, G Fluăgge38, H Geenen38, M Geisler38, W Haj Ahmad38, F Hoehle38, B Kargoll38, T Kress38, Y Kuessel38, A Kuănsken38, J Lingemann38,205, A Nowack38, I.M Nugent38, O Pooth38, A Stahl38, M Aldaya Martin39, I Asin39, N Bartosik39, J Behr39, U Behrens39, A.J Bell39, A Bethani39, K Borras39, A Burgmeier39, A Cakir39, L Calligaris39, A Campbell39, S Choudhury39, F Costanza39, C Diez Pardos39, G Dolinska39, S Dooling39, T Dorland39, G Eckerlin39, D Eckstein39, T Eichhorn39, G Flucke39, J Garay Garcia39, A Geiser39, P Gunnellini39, J Hauk39, M Hempel39,218, H Jung39, A Kalogeropoulos39, M Kasemann39, P Katsas39, J Kieseler39, C Kleinwort39, I Korol39, D Kruăcker39, W Lange39, J Leonard39, K Lipka39, A Lobanov39, W Lohmann39,218, B Lutz39, R Mankel39, I Marfin39,218, I.-A Melzer-Pellmann39, A.B Meyer39, G Mittag39, J Mnich39, A Mussgiller39, S Naumann-Emme39, A Nayak39, E Ntomari39, H Perrey39, D Pitzl39, R Placakyte39, A Raspereza39, P.M Ribeiro Cipriano39, B Roland39, E Ron39, M.Oă Sahin39, J Salfeld-Nebgen39, P Saxena39, T Schoerner-Sadenius39, M Schroăder39, C Seitz39, S Spannagel39, A.D.R Vargas Trevino39, R Walsh39, C Wissing39, V Blobel40, M Centis Vignali40, A.R Draeger40, J Erfle40, E Garutti40, K Goebel40, M Goărner40, J Haller40, M Hoffmann40, R.S Hoăing40, A Junkes40, H Kirschenmann40, R Klanner40, R Kogler40, J Lange40, T Lapsien40, T Lenz40, I Marchesini40, J Ott40, T Peiffer40, A Perieanu40, N Pietsch40, J Poehlsen40, T Poehlsen40, D Rathjens40, C Sander40, G2015 H Schettler40, P Schleper40, E Schlieckau40, A Schmidt40, M Seidel40, V Sola40, H Stadie40, G Steinbruăck40, D Troendle40, E Usai40, L Vanelderen40, A Vanhoefer40, C Barth41, C Baus41, J Berger41, C Boăser41, E Butz41, T Chwalek41, W De Boer41, A Descroix41, A Dierlamm41, M Feindt41, F Frensch41, M Giffels41, A Gilbert41, F Hartmann41,205, T Hauth41, U Husemann41, I Katkov41,208, A Kornmayer41,205, E Kuznetsova41, P Lobelle Pardo41, M.U Mozer41, T Muăller41, Th Muăller41, A Nuărnberg41, G Quast41, K Rabbertz41, S Roăcker41, H.J Simonis41, F.M Stober41, R Ulrich41, J Wagner-Kuhr41, S Wayand41, T Weiler41, R Wolf41, G Anagnostou42, G Daskalakis42, T Geralis42, V.A Giakoumopoulou42, A Kyriakis42, D Loukas42, A Markou42, C Markou42, A Psallidas42, I Topsis-Giotis42, A Agapitos43, S Kesisoglou43, A Panagiotou43, N Saoulidou43, E Stiliaris43, X Aslanoglou44, I Evangelou44, G Flouris44, C Foudas44, P Kokkas44, N Manthos44, I Papadopoulos44, E Paradas44, J Strologas44, G Bencze45, C Hajdu45, P Hidas45, D Horvath45,219, F Sikler45, V Veszpremi45, G Vesztergombi45,220, A.J Zsigmond45, N Beni46, S Czellar46, J Karancsi46,221, J Molnar46, J Palinkas46, Z Szillasi46, A Makovec47, P Raics47, Z.L Trocsanyi47, B Ujvari47, N Sahoo48, S.K Swain48, S.B Beri49, V Bhatnagar49, R Gupta49, U.Bhawandeep49, A.K Kalsi49, M Kaur49, R Kumar49, M Mittal49, N Nishu49, J.B Singh49, Ashok Kumar50, Arun Kumar50, S Ahuja50, A Bhardwaj50, B.C Choudhary50, A Kumar50, S Malhotra50, M Naimuddin50, K Ranjan50, V Sharma50, S Banerjee51, S Bhattacharya51, K Chatterjee51, S Dutta51, B Gomber51, Sa Jain51, Sh Jain51, R Khurana51, A Modak51, S Mukherjee51, D Roy51, S Sarkar51, M Sharan51, A Abdulsalam52, D Dutta52, S Kailas52, V Kumar52, A.K Mohanty52,205, L.M Pant52, P Shukla52, A Topkar52, T Aziz53, S Banerjee53, S Bhowmik53,222, R.M Chatterjee53, R.K Dewanjee53, S Dugad53, S Ganguly53, S Ghosh53, M Guchait53, A Gurtu53,223, G Kole53, S Kumar53, M Maity53,222, G Majumder53, K Mazumdar53, G.B Mohanty53, B Parida53, K Sudhakar53, N Wickramage53,224, H Bakhshiansohi54, H Behnamian54, S.M Etesami54,225, A Fahim54,226, R Goldouzian54, M Khakzad54, M Mohammadi Najafabadi54, M Naseri54, S Paktinat Mehdiabadi54, F Rezaei Hosseinabadi54, B Safarzadeh54,227, M Zeinali54, M Felcini55, M Grunewald55, M Abbrescia57,58, C Calabria57,58, S.S Chhibra57,58, A Colaleo57, D Creanza57,59, N De Filippis57,59, M De Palma57,58, L Fiore57, G Iaselli57,59, G Maggi57,59, M Maggi57, S My57,59, S Nuzzo57,58, A Pompili57,58, G Pugliese57,59, R Radogna57,58,205, G Selvaggi57,58, A Sharma57, L Silvestris57,205, R Venditti57,58, P Verwilligen57, G Abbiendi61, A.C Benvenuti61, D Bonacorsi61,62, S Braibant-Giacomelli61,62, L Brigliadori61,62, R Campanini61,62, P Capiluppi61,62, A Castro61,62, F.R Cavallo61, G Codispoti61,62, M Cuffiani61,62, G.M Dallavalle61, F Fabbri61, A Fanfani61,62, D Fasanella61,62, P Giacomelli61, C Grandi61, L Guiducci61,62, S Marcellini61, G Masetti61, A Montanari61, F.L Navarria61,62, A Perrotta61, F Primavera61,62, A.M Rossi61,62, T Rovelli61,62, G.P Siroli61,62, N Tosi61,62, R Travaglini61,62, S Albergo64,65, G Cappello64, M Chiorboli64,65, S Costa64,65, F Giordano64,205, R Potenza64,65, A Tricomi64,65, C Tuve64,65, G Barbagli68, V Ciulli68,69, C Civinini68, R D’Alessandro68,69, E Focardi68,69, E Gallo68, S Gonzi68,69, V Gori68,69, P Lenzi68,69, M Meschini68, S Paoletti68, G Sguazzoni68, A Tropiano68,69, L Benussi70, S Bianco70, F Fabbri70, D Piccolo70, R Ferretti72,73, F Ferro72, M Lo Vetere72,73, E Robutti72, S Tosi72,73, M.E Dinardo75,76, S Fiorendi75,76, S Gennai75,205, R Gerosa75,76,205, A Ghezzi75,76, P Govoni75,76, M.T Lucchini75,76,205, S Malvezzi75, R.A Manzoni75,76, A Martelli75,76, B Marzocchi75,76,205, D Menasce75, L Moroni75, M Paganoni75,76, D Pedrini75, S Ragazzi75,76, N Redaelli75, T Tabarelli de Fatis75,76, S Buontempo78, N Cavallo78,80, S Di Guida78,81,205, F Fabozzi78,80, A.O.M Iorio78,79, L Lista78, S Meola78,81,205, M Merola78, P Paolucci78,205, P Azzi83, N Bacchetta83, D Bisello83,84, A Branca83,84, R Carlin83,84, P Checchia83, M Dall’Osso83,84, T Dorigo83, U Dosselli83, M Galanti83,84, F Gasparini83,84, U Gasparini83,84, P Giubilato83,84, A Gozzelino83, K Kanishchev83,85, S Lacaprara83, M Margoni83,84, A.T Meneguzzo83,84, J Pazzini83,84, N Pozzobon83,84, P Ronchese83,84, F Simonetto83,84, E Torassa83, M Tosi83,84, P Zotto83,84, A Zucchetta83,84, G Zumerle83,84, M Gabusi87,88, S.P Ratti87,88, V Re87, C Riccardi87,88, P Salvini87, P Vitulo87,88, M Biasini90,91, G.M Bilei90, D Ciangottini90,91,205, L Fano`90,91, P Lariccia90,91, G Mantovani90,91, M Menichelli90, A Saha90, A Santocchia90,91, A Spiezia90,91,205, K Androsov93,228, P Azzurri93, G Bagliesi93, J Bernardini93, T Boccali93, G Broccolo93,95, R Castaldi93, M.A Ciocci93,228, R Dell’Orso93, S Donato93,95,205, F Fiori93,95, L Foa`93,95, A Giassi93, M.T Grippo93,228, F Ligabue93,95, T Lomtadze93, L Martini93,94, A Messineo93,94, C.S Moon93,229, F Palla93,205, A Rizzi93,94, A Savoy-Navarro93,230, A.T Serban93, P Spagnolo93, P Squillacioti93,228, R Tenchini93, G Tonelli93,94, A Venturi93, P.G Verdini93, C Vernieri93,95, L Barone97,98, F Cavallari97, G D’imperio97,98, D Del Re97,98, M Diemoz97, C Jorda97, E Longo97,98, F Margaroli97,98, P Meridiani97, F Micheli97,98,205, S Nourbakhsh97,98, G Organtini97,98, R Paramatti97, S Rahatlou97,98, C Rovelli97, F Santanastasio97,98, L Soffi97,98, P Traczyk97,98,205, N Amapane100,101, R Arcidiacono100,102, S Argiro100,101, M Arneodo100,102, R Bellan100,101, C Biino100, N Cartiglia100, S Casasso100,101,205, M Costa100,101, A Degano100,101, N Demaria100, L Finco100,101,205, C Mariotti100, S Maselli100, E Migliore100,101, V Monaco100,101, M Musich100, M.M Obertino100,102, L Pacher100,101, N Pastrone100, M Pelliccioni100, G.L Pinna Angioni100,101, A Potenza100,101, A Romero100,101, M Ruspa100,102, R Sacchi100,101, A Solano100,101, A Staiano100, U Tamponi100, S Belforte104, V Candelise104,105,205, M Casarsa104, F Cossutti104, G Della Ricca104,105, B Gobbo104, C La Licata104,105, M Marone104,105, A Schizzi104,105, T Umer104,105, A Zanetti104, S Chang106, A Kropivnitskaya106, S.K Nam106, D.H Kim107, G.N Kim107, M.S Kim107, D.J Kong107, S Lee107, Y.D Oh107, H Park107, A Sakharov107, D.C Son107, T.J Kim108, J.Y Kim109, S Song109, S Choi110, D Gyun110, B Hong110, M Jo110, H Kim110, Y Kim110, B Lee110, K.S Lee110, S.K Park110, Y Roh110, H.D Yoo111, M Choi112, J.H Kim112, I.C Park112, G Ryu112, M.S Ryu112, Y Choi113, Y.K Choi113, J Goh113, D Kim113, E Kwon113, J Lee113, I Yu113, A Juodagalvis114, J.R Komaragiri115, M.A.B Md Ali115, E Casimiro Linares116, H Castilla-Valdez116, E De La Cruz-Burelo116, I Heredia-de La Cruz116,231, A Hernandez-Almada116, R Lopez-Fernandez116, A Sanchez-Hernandez116, S Carrillo Moreno117, F Vazquez Valencia117, I Pedraza118, H.A Salazar Ibarguen118, A Morelos Pineda119, D Krofcheck120, P.H Butler121, S Reucroft121, A Ahmad122, M Ahmad122, Q Hassan122, H.R Hoorani122, W.A Khan122, T Khurshid122, M Shoaib122, Macmillan Publishers Limited All rights reserved RESEARCH LETTER H Bialkowska123, M Bluj123, B Boimska123, T Frueboes123, M Go´rski123, M Kazana123, K Nawrocki123, K Romanowska-Rybinska123, M Szleper123, P Zalewski123, G Brona124, K Bunkowski124, M Cwiok124, W Dominik124, K Doroba124, A Kalinowski124, M Konecki124, J Krolikowski124, M Misiura124, M Olszewski124, W Wolszczak124, P Bargassa125, C Beira˜o Da Cruz E Silva125, P Faccioli125, P.G Ferreira Parracho125, M Gallinaro125, L Lloret Iglesias125, F Nguyen125, J Rodrigues Antunes125, J Seixas125, J Varela125, P Vischia125, S Afanasiev126, P Bunin126, M Gavrilenko126, I Golutvin126, I Gorbunov126, A Kamenev126, V Karjavin126, V Konoplyanikov126, A Lanev126, A Malakhov126, V Matveev126,232, P Moisenz126, V Palichik126, V Perelygin126, S Shmatov126, N Skatchkov126, V Smirnov126, A Zarubin126, V Golovtsov127, Y Ivanov127, V Kim127,233, P Levchenko127, V Murzin127, V Oreshkin127, I Smirnov127, V Sulimov127, L Uvarov127, S Vavilov127, A Vorobyev127, An Vorobyev127, Yu Andreev128, A Dermenev128, S Gninenko128, N Golubev128, M Kirsanov128, N Krasnikov128, A Pashenkov128, D Tlisov128, A Toropin128, V Epshteyn129, V Gavrilov129, N Lychkovskaya129, V Popov129, I Pozdnyakov129, G Safronov129, S Semenov129, A Spiridonov129, V Stolin129, E Vlasov129, A Zhokin129, V Andreev130, M Azarkin130, I Dremin130, M Kirakosyan130, A Leonidov130, G Mesyats130, S.V Rusakov130, A Vinogradov130, A Belyaev131, E Boos131, M Dubinin131,234, L Dudko131, A Ershov131, A Gribushin131, V Klyukhin131, O Kodolova131, I Lokhtin131, S Obraztsov131, S Petrushanko131, V Savrin131, A Snigirev131, I Azhgirey132, I Bayshev132, S Bitioukov132, V Kachanov132, A Kalinin132, D Konstantinov132, V Krychkine132, V Petrov132, R Ryutin132, A Sobol132, L Tourtchanovitch132, S Troshin132, N Tyurin132, A Uzunian132, A Volkov132, P Adzic133,235, M Ekmedzic133, J Milosevic133, V Rekovic133, J Alcaraz Maestre134, C Battilana134, E Calvo134, M Cerrada134, M Chamizo Llatas134, N Colino134, B De La Cruz134, A Delgado Peris134, D Domı´nguez Va´zquez134, A Escalante Del Valle134, C Fernandez Bedoya134, J.P Ferna´ndez Ramos134, J Flix134, M.C Fouz134, P Garcia-Abia134, O Gonzalez Lopez134, S Goy Lopez134, J.M Hernandez134, M.I Josa134, E Navarro De Martino134, A Pe´rez-Calero Yzquierdo134, J Puerta Pelayo134, A Quintario Olmeda134, I Redondo134, L Romero134, M.S Soares134, C Albajar135, J.F de Troco´niz135, M Missiroli135, D Moran135, H Brun136, J Cuevas136, J Fernandez Menendez136, S Folgueras136, I Gonzalez Caballero136, J.A Brochero Cifuentes137, I.J Cabrillo137, A Calderon137, J Duarte Campderros137, M Fernandez137, G Gomez137, A Graziano137, A Lopez Virto137, J Marco137, R Marco137, C Martinez Rivero137, F Matorras137, F.J Munoz Sanchez137, J Piedra Gomez137, T Rodrigo137, A.Y Rodrı´guez-Marrero137, A RuizJimeno137, L Scodellaro137, I Vila137, R Vilar Cortabitarte137, D Abbaneo138, E Auffray138, G Auzinger138, M Bachtis138, P Baillon138, A.H Ball138, D Barney138, A Benaglia138, J Bendavid138, L Benhabib138, J.F Benitez138, C Bernet138,210, P Bloch138, A Bocci138, A Bonato138, O Bondu138, C Botta138, H Breuker138, T Camporesi138, G Cerminara138, S Colafranceschi138,236, M D’Alfonso138, D d’Enterria138, A Dabrowski138, A David138, F De Guio138, A De Roeck138, S De Visscher138, E Di Marco138, M Dobson138, M Dordevic138, N Dupont-Sagorin138, A Elliott-Peisert138, G Franzoni138, W Funk138, D Gigi138, K Gill138, D Giordano138, M Girone138, F Glege138, R Guida138, S Gundacker138, M Guthoff138, J Hammer138, M Hansen138, P Harris138, J Hegeman138, V Innocente138, P Janot138, K Kousouris138, K Krajczar138, P Lecoq138, C Lourenỗo138, N Magini138, L Malgeri138, M Mannelli138, J Marrouche138, L Masetti138, F Meijers138, S Mersi138, E Meschi138, F Moortgat138, S Morovic138, M Mulders138, L Orsini138, L Pape138, E Perez138, L Perrozzi138, A Petrilli138, G Petrucciani138, A Pfeiffer138, M Pimiaă138, D Piparo138, M Plagge138, A Racz138, G Rolandi138,237, M Rovere138, H Sakulin138, C Schaăfer138, C Schwick138, A Sharma138, P Siegrist138, P Silva138, M Simon138, P Sphicas138,238, D Spiga138, J Steggemann138, B Stieger138, M Stoye138, Y Takahashi138, D Treille138, A Tsirou138, G.I Veres138,220, N Wardle138, H.K Woăhri138, H Wollny138, W.D Zeuner138, W Bertl139, K Deiters139, W Erdmann139, R Horisberger139, Q Ingram139, H.C Kaestli139, D Kotlinski139, D Renker139, T Rohe139, F Bachmair140, L Baăni140, L Bianchini140, M.A Buchmann140, B Casal140, N Chanon140, G Dissertori140, M Dittmar140, M Donega`140, M Duănser140, P Eller140, C Grab140, D Hits140, J Hoss140, W Lustermann140, B Mangano140, A.C Marini140, M Marionneau140, P Martinez Ruiz del Arbol140, M Masciovecchio140, D Meister140, N Mohr140, P Musella140, C Naăgeli140,239, F Nessi-Tedaldi140, F Pandolfi140, F Pauss140, M Peruzzi140, M Quittnat140, L Rebane140, M Rossini140, A Starodumov140,240, M Takahashi140, K Theofilatos140, R Wallny140, H.A Weber140, C Amsler141,241, M.F Canelli141, V Chiochia141, A De Cosa141, A Hinzmann141, T Hreus141, B Kilminster141, C Lange141, B Millan Mejias141, J Ngadiuba141, D Pinna141, P Robmann141, F.J Ronga141, S Taroni141, M Verzetti141, Y Yang141, M Cardaci142, K.H Chen142, C Ferro142, C.M Kuo142, W Lin142, Y.J Lu142, R Volpe142, S.S Yu142, P Chang143, Y.H Chang143, Y.W Chang143, Y Chao143, K.F Chen143, P.H Chen143, C Dietz143, U Grundler143, W.-S Hou143, K.Y Kao143, Y.F Liu143, R.-S Lu143, D Majumder143, E Petrakou143, Y.M Tzeng143, R Wilken143, B Asavapibhop144, G Singh144, N Srimanobhas144, N Suwonjandee144, A Adiguzel145, M.N Bakirci145,242, S Cerci145,243, C Dozen145, I Dumanoglu145, E Eskut145, S Girgis145, G Gokbulut145, E Gurpinar145, I Hos145, E.E Kangal145, A Kayis Topaksu145, G Onengut145,244, K Ozdemir145, S Ozturk145,242, A Polatoz145, D Sunar Cerci145,243, B Tali145,243, H Topakli145,242, M Vergili145, I.V Akin146, B Bilin146, S Bilmis146, H Gamsizkan146,245, B Isildak146,246, G Karapinar146,247, K Ocalan146,248, S Sekmen146, U.E Surat146, M Yalvac146, M Zeyrek146, E.A Albayrak147,249, E Guălmez147, M Kaya147,250, O Kaya147,251, T Yetkin147,252, K Cankocak148, F.I Vardarlı148, L Levchuk149, P Sorokin149, J.J Brooke150, E Clement150, D Cussans150, H Flacher150, J Goldstein150, M Grimes150, G.P Heath150, H.F Heath150, J Jacob150, L Kreczko150, C Lucas150, Z Meng150, D.M Newbold150,253, S Paramesvaran150, A Poll150, T Sakuma150, S Senkin150, V.J Smith150, K.W Bell151, A Belyaev151,254, C Brew151, R.M Brown151, D.J.A Cockerill151, J.A Coughlan151, K Harder151, S Harper151, E Olaiya151, D Petyt151, C.H Shepherd-Themistocleous151, A Thea151, I.R Tomalin151, T Williams151, W.J Womersley151, S.D Worm151, M Baber152, R Bainbridge152, O Buchmuller152, D Burton152, D Colling152, N Cripps152, P Dauncey152, G Davies152, M Della Negra152, P Dunne152, W Ferguson152, J Fulcher152, D Futyan152, G Hall152, G Iles152, M Jarvis152, G Karapostoli152, M Kenzie152, R Lane152, R Lucas152,253, L Lyons152, A.-M Magnan152, S Malik152, B Mathias152, G2015 J Nash152, A Nikitenko152,240, J Pela152, M Pesaresi152, K Petridis152, D.M Raymond152, S Rogerson152, A Rose152, C Seez152, P Sharp152{, A Tapper152, M Vazquez Acosta152, T Virdee152, S.C Zenz152, J.E Cole153, P.R Hobson153, A Khan153, P Kyberd153, D Leggat153, D Leslie153, I.D Reid153, P Symonds153, L Teodorescu153, M Turner153, J Dittmann154, K Hatakeyama154, A Kasmi154, H Liu154, T Scarborough154, O Charaf155, S.I Cooper155, C Henderson155, P Rumerio155, A Avetisyan156, T Bose156, C Fantasia156, P Lawson156, C Richardson156, J Rohlf156, J St John156, L Sulak156, J Alimena157, E Berry157, S Bhattacharya157, G Christopher157, D Cutts157, Z Demiragli157, N Dhingra157, A Ferapontov157, A Garabedian157, U Heintz157, G Kukartsev157, E Laird157, G Landsberg157, M Luk157, M Narain157, M Segala157, T 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Weng166, L Winstrom166, P Wittich166, D Winn167, S Abdullin168, M Albrow168, J Anderson168, G Apollinari168, L.A.T Bauerdick168, A Beretvas168, J Berryhill168, P.C Bhat168, G Bolla168, K Burkett168, J.N Butler168, H.W.K Cheung168, F Chlebana168, S Cihangir168, V.D Elvira168, I Fisk168, J Freeman168, Y Gao168, E Gottschalk168, L Gray168, D Green168, S Gruănendahl168, O Gutsche168, J Hanlon168, D Hare168, R.M Harris168, J Hirschauer168, B Hooberman168, S Jindariani168, M Johnson168, U Joshi168, K Kaadze168, B Klima168, B Kreis168, S Kwan168{, J Linacre168, D Lincoln168, R Lipton168, T Liu168, J Lykken168, K Maeshima168, J.M Marraffino168, V.I Martinez Outschoorn168, S Maruyama168, D Mason168, P McBride168, P Merkel168, K Mishra168, S Mrenna168, S Nahn168, C Newman-Holmes168, V O’Dell168, O Prokofyev168, E Sexton-Kennedy168, S Sharma168, A Soha168, W.J Spalding168, L Spiegel168, L Taylor168, S Tkaczyk168, N.V Tran168, L Uplegger168, E.W Vaandering168, R Vidal168, A Whitbeck168, J Whitmore168, F Yang168, D Acosta169, P Avery169, P Bortignon169, D Bourilkov169, M Carver169, D Curry169, S Das169, M De Gruttola169, G.P Di Giovanni169, R.D Field169, M Fisher169, I.K Furic169, J Hugon169, J Konigsberg169, A Korytov169, T Kypreos169, J.F Low169, K Matchev169, H Mei169, P Milenovic169,255, G Mitselmakher169, L Muniz169, A Rinkevicius169, L Shchutska169, M Snowball169, D Sperka169, J Yelton169, M Zakaria169, S Hewamanage170, S Linn170, P Markowitz170, G Martinez170, J.L Rodriguez170, T Adams171, A Askew171, J Bochenek171, B Diamond171, J Haas171, S Hagopian171, V Hagopian171, K.F Johnson171, H Prosper171, V Veeraraghavan171, M Weinberg171, M.M Baarmand172, M Hohlmann172, H Kalakhety172, F Yumiceva172, M.R Adams173, L Apanasevich173, D Berry173, R.R Betts173, I Bucinskaite173, R Cavanaugh173, O Evdokimov173, L Gauthier173, C.E Gerber173, D.J Hofman173, P Kurt173, D.H Moon173, C O’Brien173, I.D Sandoval Gonzalez173, C Silkworth173, P Turner173, N Varelas173, B 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Pollack186, A Pozdnyakov186, M Schmitt186, S Stoynev186, K Sung186, M Velasco186, S Won186, Macmillan Publishers Limited All rights reserved LETTER RESEARCH A Brinkerhoff187, K.M Chan187, A Drozdetskiy187, M Hildreth187, C Jessop187, D.J Karmgard187, N Kellams187, K Lannon187, S Lynch187, N Marinelli187, Y Musienko187,232, T Pearson187, M Planer187, R Ruchti187, G Smith187, N Valls187, M Wayne187, M Wolf187, A Woodard187, L Antonelli188, J Brinson188, B Bylsma188, L.S Durkin188, S Flowers188, A Hart188, C Hill188, R Hughes188, K Kotov188, T.Y Ling188, W Luo188, D Puigh188, M Rodenburg188, B.L Winer188, H Wolfe188, H.W Wulsin188, O Driga189, P Elmer189, J Hardenbrook189, P Hebda189, A Hunt189, S.A Koay189, P Lujan189, D Marlow189, T Medvedeva189, M Mooney189, J Olsen189, P Piroue´189, X Quan189, H Saka189, D Stickland189,205, C Tully189, J.S Werner189, A Zuranski189, E Brownson190, S Malik190, H Mendez190, J.E Ramirez Vargas190, V.E Barnes191, D Benedetti191, D Bortoletto191, M De Mattia191, L Gutay191, Z Hu191, M.K Jha191, M Jones191, K Jung191, M Kress191, N Leonardo191, D.H Miller191, N Neumeister191, B.C Radburn-Smith191, X Shi191, I Shipsey191, D Silvers191, A Svyatkovskiy191, F Wang191, W Xie191, L Xu191, J Zablocki191, N Parashar192, J Stupak192, A Adair193, B Akgun193, K.M Ecklund193, F.J.M Geurts193, W Li193, B Michlin193, B.P Padley193, R Redjimi193, J Roberts193, J Zabel193, B Betchart194, A Bodek194, R Covarelli194, P de Barbaro194, R Demina194, Y Eshaq194, T Ferbel194, A Garcia-Bellido194, P Goldenzweig194, J Han194, A Harel194, A Khukhunaishvili194, S Korjenevski194, G Petrillo194, D Vishnevskiy194, R Ciesielski195, L Demortier195, K Goulianos195, C Mesropian195, S Arora196, A Barker196, J.P Chou196, C ContrerasCampana196, E Contreras-Campana196, D Duggan196, D Ferencek196, Y Gershtein196, R Gray196, E Halkiadakis196, D Hidas196, S Kaplan196, A Lath196, S Panwalkar196, M Park196, R Patel196, S Salur196, S Schnetzer196, S Somalwar196, R Stone196, S Thomas196, P Thomassen196, M Walker196, K Rose197, S Spanier197, A York197, O Bouhali198,258, A Castaneda Hernandez198, R Eusebi198, W Flanagan198, J Gilmore198, T Kamon198,259, V Khotilovich198, V Krutelyov198, R Montalvo198, I Osipenkov198, Y Pakhotin198, A Perloff198, J Roe198, A Rose198, A Safonov198, I Suarez198, A Tatarinov198, K.A Ulmer198, N Akchurin199, C Cowden199, J Damgov199, C Dragoiu199, P.R Dudero199, J Faulkner199, K Kovitanggoon199, S Kunori199, S.W Lee199, T Libeiro199, I Volobouev199, E Appelt200, A.G Delannoy200, S Greene200, A Gurrola200, W Johns200, C Maguire200, Y Mao200, A Melo200, M Sharma200, P Sheldon200, B Snook200, S Tuo200, J Velkovska200, M.W Arenton201, S Boutle201, B Cox201, B Francis201, J Goodell201, R Hirosky201, A Ledovskoy201, H Li201, C Lin201, C Neu201, J Wood201, C Clarke202, R Harr202, P.E Karchin202, C Kottachchi Kankanamge Don202, P Lamichhane202, J Sturdy202, D.A Belknap203, D Carlsmith203, M Cepeda203, S Dasu203, L Dodd203, S Duric203, E Friis203, R Hall-Wilton203, M Herndon203, A Herve´203, P Klabbers203, A Lanaro203, C Lazaridis203, A Levine203, R Loveless203, A Mohapatra203, I Ojalvo203, T Perry203, G.A Pierro203, G Polese203, I Ross203, T Sarangi203, A Savin203, W.H Smith203, D Taylor203, C Vuosalo203 & N Woods203 Primary affiliations Yerevan Physics Institute, Yerevan, Armenia 2Institut fuăr Hochenergiephysik der OeAW, Wien, Austria 3National Centre for Particle and High Energy Physics, Minsk, Belarus 4Universiteit Antwerpen, Antwerpen, Belgium 5Vrije Universiteit Brussel, Brussel, Belgium 6Universite´ Libre de Bruxelles, Bruxelles, Belgium 7Ghent University, Ghent, Belgium 8Universite´ Catholique de Louvain, Louvain-la-Neuve, Belgium Universite´ de Mons, Mons, Belgium 10Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil 11Universidade Estado Rio de Janeiro, Rio de Janeiro, Brazil 12 Universidade Estadual Paulista, Universidade Federal ABC, Sa˜o Paulo, Brazil 13 Universidade Estadual Paulista 14Universidade Federal ABC 15Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria 16University of Sofia, Sofia, Bulgaria 17Institute of High Energy Physics, Beijing, China 18State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China 19Universidad de Los Andes, Bogota, Colombia 20University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split, Croatia 21University of Split, Faculty of Science, Split, Croatia 22Institute Rudjer Boskovic, Zagreb, Croatia 23 University of Cyprus, Nicosia, Cyprus 24Charles University, Prague, Czech Republic 25 Academy of Scientific Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt 26National Institute of Chemical Physics and Biophysics, Tallinn, Estonia 27Department of Physics, University of Helsinki, Helsinki, Finland 28Helsinki Institute of Physics, Helsinki, Finland 29 Lappeenranta University of Technology, Lappeenranta, Finland 30DSM/IRFU, CEA/ Saclay, Gif-sur-Yvette, France 31Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France 32Institut Pluridisciplinaire Hubert Curien, Universite´ de Strasbourg, Universite´ de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France 33 Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules, CNRS/IN2P3, Villeurbanne, France 34Universite´ de Lyon, Universite´ Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucle´aire de Lyon, Villeurbanne, France 35Institute of High Energy Physics and Informatization, Tbilisi State University, Tbilisi, Georgia 36RWTH Aachen University, I Physikalisches Institut, Aachen, Germany 37 RWTH Aachen University, III Physikalisches Institut A, Aachen, Germany 38RWTH Aachen University, III Physikalisches Institut B, Aachen, Germany 39Deutsches Elektronen-Synchrotron, Hamburg, Germany 40University of Hamburg, Hamburg, Germany 41Institut fuăr Experimentelle Kernphysik, Karlsruhe, Germany 42Institute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi, Greece 43 University of Athens, Athens, Greece 44University of Ioa´nnina, Ioa´nnina, Greece 45 Wigner Research Centre for Physics, Budapest, Hungary 46Institute of Nuclear Research ATOMKI, Debrecen, Hungary 47University of Debrecen, Debrecen, Hungary 48 National Institute of Science Education and Research, Bhubaneswar, India 49Panjab University, Chandigarh, India 50University of Delhi, Delhi, India 51Saha Institute of Nuclear Physics, Kolkata, India 52Bhabha Atomic Research Centre, Mumbai, India 53 Tata Institute of Fundamental Research, Mumbai, India 54Institute for Research in Fundamental Sciences (IPM), Tehran, Iran 55University College Dublin, Dublin, Ireland 56 INFN Sezione di Bari, Universita` di Bari, Politecnico di Bari, Bari, Italy 57INFN Sezione di Bari 58Universita` di Bari 59Politecnico di Bari 60INFN Sezione di Bologna, Universita` G2015 di Bologna, Bologna, Italy 61INFN Sezione di Bologna 62Universita` di Bologna 63INFN Sezione di Catania, Universita` di Catania, CSFNSM, Catania, Italy 64INFN Sezione di Catania 65Universita` di Catania 66CSFNSM 67INFN Sezione di Firenze, Universita` di Firenze, Firenze, Italy 68INFN Sezione di Firenze 69Universita` di Firenze 70INFN Laboratori Nazionali di Frascati, Frascati, Italy 71INFN Sezione di Genova, Universita` di Genova, Genova, Italy 72INFN Sezione di Genova 73Universita` di Genova 74INFN Sezione di Milano-Bicocca, Universita` di Milano-Bicocca, Milano, Italy 75INFN Sezione di Milano-Bicocca 76Universita` di Milano-Bicocca 77INFN Sezione di Napoli, Universita` di Napoli ’Federico II’, Universita` della Basilicata (Potenza), Universita` G Marconi (Roma), Napoli, Italy 78INFN Sezione di Napoli 79Universita` di Napoli ’Federico II’ 80 Universita` della Basilicata (Potenza) 81Universita` G Marconi (Roma) 82INFN Sezione di Padova, Universita` di Padova, Universita` di Trento (Trento), Padova, Italy 83INFN Sezione di Padova 84Universita` di Padova 85Universita` di Trento (Trento) 86INFN Sezione di Pavia, Universita` di Pavia, Pavia, Italy 87INFN Sezione di Pavia 88Universita` di Pavia 89INFN Sezione di Perugia, Universita` di Perugia, Perugia, Italy 90INFN Sezione di Perugia 91Universita` di Perugia 92INFN Sezione di Pisa, Universita` di Pisa, Scuola Normale Superiore di Pisa, Pisa, Italy 93INFN Sezione di Pisa 94Universita` di Pisa 95 Scuola Normale Superiore di Pisa 96INFN Sezione di Roma, Universita` di Roma, Roma, Italy 97INFN Sezione di Roma 98Universita` di Roma 99INFN Sezione di Torino, Universita` di Torino, Universita` del Piemonte Orientale (Novara), Torino, Italy 100INFN Sezione di Torino 101Universita` di Torino 102Universita` del Piemonte Orientale (Novara) 103INFN Sezione di Trieste, Universita` di Trieste, Trieste, Italy 104INFN Sezione di Trieste 105Universita` di Trieste 106Kangwon National University, Chunchon, Korea 107 Kyungpook National University, Daegu, Korea 108Chonbuk National University, Jeonju, Korea 109Chonnam National University, Institute for Universe and Elementary Particles, Kwangju, Korea 110Korea University, Seoul, Korea 111Seoul National University, Seoul, Korea 112University of Seoul, Seoul, Korea 113Sungkyunkwan University, Suwon, Korea 114Vilnius University, Vilnius, Lithuania 115National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia 116Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico 117Universidad Iberoamericana, Mexico City, Mexico 118Benemerita Universidad Autonoma de Puebla, Puebla, Mexico 119 Universidad Auto´noma de San Luis Potosı´, San Luis Potosı´, Mexico 120University of Auckland, Auckland, New Zealand 121University of Canterbury, Christchurch, New Zealand 122National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan 123 National Centre for Nuclear Research, Swierk, Poland 124Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland 125Laborato´rio de Instrumentaỗao e Fsica Experimental de Partculas, Lisboa, Portugal 126Joint Institute for Nuclear Research, Dubna, Russia 127Petersburg Nuclear Physics Institute, Gatchina (St Petersburg), Russia 128Institute for Nuclear Research, Moscow, Russia 129Institute for Theoretical and Experimental Physics, Moscow, Russia 130P.N Lebedev Physical Institute, Moscow, Russia 131Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia 132State Research Center of Russian Federation, Institute for High Energy Physics, Protvino, Russia 133University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia 134Centro de Investigaciones Energe´ticas Medioambientales y Tecnolo´gicas (CIEMAT), Madrid, Spain 135Universidad Auto´noma de Madrid, Madrid, Spain 136Universidad de Oviedo, Oviedo, Spain 137Instituto de Fı´sica de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain 138CERN, European Organization for Nuclear Research, Geneva, Switzerland 139Paul Scherrer Institut, Villigen, Switzerland 140Institute for Particle Physics, ETH Zurich, Zurich, Switzerland 141Universitaăt Zuărich, Zurich, Switzerland 142National Central University, Chung-Li, Taiwan 143National Taiwan University (NTU), Taipei, Taiwan 144Chulalongkorn University, Faculty of Science, Department of Physics, Bangkok, Thailand 145Cukurova University, Adana, Turkey 146 Middle East Technical University, Physics Department, Ankara, Turkey 147Bogazici University, Istanbul, Turkey 148Istanbul Technical University, Istanbul, Turkey 149 National Scientific Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine 150University of Bristol, Bristol, United Kingdom 151Rutherford Appleton Laboratory, Didcot, United Kingdom 152Imperial College, London, United Kingdom 153 Brunel University, Uxbridge, United Kingdom 154Baylor University, Waco, USA 155 The University of Alabama, Tuscaloosa, USA 156Boston University, Boston, USA 157 Brown University, Providence, USA 158University of California, Davis, Davis, USA 159 University of California, Los Angeles, USA 160University of California, Riverside, Riverside, USA 161University of California, San Diego, La Jolla, USA 162University of California, Santa Barbara, Santa Barbara, USA 163California Institute of Technology, Pasadena, USA 164Carnegie Mellon University, Pittsburgh, USA 165University of Colorado at Boulder, Boulder, USA 166Cornell University, Ithaca, USA 167Fairfield University, Fairfield, USA 168Fermi National Accelerator Laboratory, Batavia, USA 169 University of Florida, Gainesville, USA 170Florida International University, Miami, USA 171Florida State University, Tallahassee, USA 172Florida Institute of Technology, Melbourne, USA 173University of Illinois at Chicago (UIC), Chicago, USA 174The University of Iowa, Iowa City, USA 175Johns Hopkins University, Baltimore, USA 176The University of Kansas, Lawrence, USA 177Kansas State University, Manhattan, USA 178 Lawrence Livermore National Laboratory, Livermore, USA 179University of Maryland, College Park, USA 180Massachusetts Institute of Technology, Cambridge, USA 181 University of Minnesota, Minneapolis, USA 182University of Mississippi, Oxford, USA 183 University of Nebraska-Lincoln, Lincoln, USA 184State University of New York at Buffalo, Buffalo, USA 185Northeastern University, Boston, USA 186Northwestern University, Evanston, USA 187University of Notre Dame, Notre Dame, USA 188The Ohio State University, Columbus, USA 189Princeton University, Princeton, USA 190University of Puerto Rico, Mayaguez, USA 191Purdue University, West Lafayette, USA 192Purdue University Calumet, Hammond, USA 193Rice University, Houston, USA 194University of Rochester, Rochester, USA 195The Rockefeller University, New York, USA 196Rutgers, The State University of New Jersey, Piscataway, USA 197University of Tennessee, Knoxville, USA 198Texas A&M University, College Station, USA 199Texas Tech University, Lubbock, USA 200Vanderbilt University, Nashville, USA 201University of Virginia, Charlottesville, USA 202Wayne State University, Detroit, USA 203University of Wisconsin, Madison, USA Macmillan Publishers Limited All rights reserved RESEARCH LETTER Secondary affiliations 204 Vienna University of Technology, Vienna, Austria 205CERN, European Organization for Nuclear Research, Geneva, Switzerland 206Institut Pluridisciplinaire Hubert Curien, Universite´ de Strasbourg, Universite´ de Haute Alsace Mulhouse, CNRS/IN2P3, Strasbourg, France 207National Institute of Chemical Physics and Biophysics, Tallinn, Estonia 208Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia 209Universidade Estadual de Campinas, Campinas, Brazil 210 Laboratoire Leprince-Ringuet, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, France 211 Joint Institute for Nuclear Research, Dubna, Russia 212Suez University, Suez, Egypt 213 Cairo University, Cairo, Egypt 214Fayoum University, El-Fayoum, Egypt 215Ain Shams University, Cairo, Egypt 216Now at Sultan Qaboos University, Muscat, Oman 217 Universite´ de Haute Alsace, Mulhouse, France 218Brandenburg University of Technology, Cottbus, Germany 219Institute of Nuclear Research ATOMKI, Debrecen, Hungary 220Eoătvoăs Lorand University, Budapest, Hungary 221University of Debrecen, Debrecen, Hungary 222University of Visva-Bharati, Santiniketan, India 223Now at King Abdulaziz University, Jeddah, Saudi Arabia 224University of Ruhuna, Matara, Sri Lanka 225 Isfahan University of Technology, Isfahan, Iran 226University of Tehran, Department of Engineering Science, Tehran, Iran 227Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran 228Universita` degli Studi di Siena, Siena, Italy 229Centre National de la Recherche Scientifique (CNRS) - IN2P3, Paris, France 230Purdue University, West Lafayette, USA 231Universidad Michoacana de San Nicolas de Hidalgo, Morelia, Mexico 232Institute for Nuclear Research, Moscow, Russia 233St Petersburg State Polytechnical University, St Petersburg, Russia 234 California Institute of Technology, Pasadena, USA 235Faculty of Physics, University of Belgrade, Belgrade, Serbia 236Facolta` Ingegneria, Universita` di Roma, Roma, Italy 237 Scuola Normale e Sezione dell’INFN, Pisa, Italy 238University of Athens, Athens, Greece 239Paul Scherrer Institut, Villigen, Switzerland 240Institute for Theoretical and Experimental Physics, Moscow, Russia 241Albert Einstein Center for Fundamental Physics, Bern, Switzerland 242Gaziosmanpasa University, Tokat, Turkey 243Adiyaman University, Adiyaman, Turkey 244Cag University, Mersin, Turkey 245Anadolu University, Eskisehir, Turkey 246Ozyegin University, Istanbul, Turkey 247Izmir Institute of Technology, Izmir, Turkey 248Necmettin Erbakan University, Konya, Turkey 249Mimar Sinan University, Istanbul, Istanbul, Turkey 250Marmara University, Istanbul, Turkey 251 Kafkas University, Kars, Turkey 252Yildiz Technical University, Istanbul, Turkey 253 Rutherford Appleton Laboratory, Didcot, United Kingdom 254School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom 255University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia 256 Argonne National Laboratory, Argonne, USA 257Erzincan University, Erzincan, Turkey 258Texas A&M University at Qatar, Doha, Qatar 259Kyungpook National University, Daegu, Korea {Deceased LHCb Collaboration I Bediaga1, J.M De Miranda1, F Ferreira Rodrigues1, A Gomes1,79, A Massafferri1, A.C dos Reis1, A.B Rodrigues1, S Amato2, K Carvalho Akiba2, L De Paula2, O Francisco2, M Gandelman2, A Hicheur2, J.H Lopes2, D Martins Tostes2, I Nasteva2, J.M Otalora Goicochea2, E Polycarpo2, C Potterat2, M.S Rangel2, V Salustino Guimaraes2, B Souza De Paula2, D Vieira2, L An3, Y Gao3, F Jing3, Y Li3, Z Yang3, X Yuan3, Y Zhang3, L Zhong3, L Beaucourt4, M Chefdeville4, D Decamp4, N De´le´age4, Ph Ghez4, J.-P Lees4, J.F Marchand4, M.-N Minard4, B Pietrzyk4, W Qian4, S T’Jampens4, V Tisserand4, E Tournefier4, Z Ajaltouni5, M Baalouch5, E Cogneras5, O Deschamps5, I El Rifai5, M Grabalosa Ga´ndara5, P Henrard5, M Hoballah5, R Lefe`vre5, J Maratas5, S Monteil5, V Niess5, P Perret5, C Adrover6, S Akar6, E Aslanides6, J Cogan6, W Kanso6, R Le Gac6, O Leroy6, G Mancinelli6, A Morda`6, M Perrin-Terrin6, J Serrano6, A Tsaregorodtsev6, Y Amhis7, S Barsuk7, M Borsato7, O Kochebina7, J Lefranỗois7, F Machefert7, A Martı´n Sa´nchez7, M Nicol7, P Robbe7, M.-H Schune7, M Teklishyn7, A Vallier7, B Viaud7, G Wormser7, E Ben-Haim8, M Charles8, S Coquereau8, P David8, L Del Buono8, L Henry8, F Polci8, J Albrecht9, T Brambach9, Ch Cauet9, M Deckenhoff9, U Eitschberger9, R Ekelhof9, L Gavardi9, F Kruse9, F Meier9, R Niet9, C.J Parkinson9,45, M Schlupp9, A Shires9, B Spaan9, S Swientek9, J Wishahi9, O Aquines Gutierrez10, J Blouw10, M Britsch10, M Fontana 10, D Popov10, M Schmelling10, D Volyanskyy10, M Zavertyaev10,89, S Bachmann11, A Bien11, A Comerma-Montells11, M De Cian11, F Dordei11, S Esen11, C Faărber11, E Gersabeck11, L Grillo11, X Han11, S Hansmann-Menzemer11, A Jaeger11, M Kolpin11, K Kreplin11, G Krocker11, B Leverington11, J Marks11, M Meissner11, M Neuner11, T Nikodem11, P Seyfert11, M Stahl11, S Stahl11, U Uwer11, M Vesterinen11, S Wandernoth11, D Wiedner11, A Zhelezov11, R McNulty12, R Wallace12, W.C Zhang12, A Palano13,84, A Carbone14,74, A Falabella14, D Galli14,74, U Marconi14, N Moggi14, M Mussini14, S Perazzini14,74, V Vagnoni14, G Valenti14, M Zangoli14, W Bonivento15,38, S Cadeddu15, A Cardini15, V Cogoni15, A Contu15,38, A Lai15, B Liu15, G Manca15,82, R Oldeman15,82, B Saitta15,82, C Vacca15, M Andreotti16,69, W Baldini16, C Bozzi16, R Calabrese16,69, M Corvo16,69, M Fiore16,69, M Fiorini16,69, E Luppi16,69, L.L Pappalardo16,69, I Shapoval16,43,69, G Tellarini16,69, L Tomassetti16,69, S Vecchi16, L Anderlini17,68, A Bizzeti17,71, M Frosini17,68, G Graziani17, G Passaleva17, M Veltri17,88, G Bencivenni18, P Campana18, P De Simone18, G Lanfranchi18, M Palutan18, M Rama18, A Sarti18,86, B Sciascia18, R Vazquez Gomez18, R Cardinale19,38,76, F Fontanelli19,76, S Gambetta19,76, C Patrignani19,76, A Petrolini19,76, A Pistone19, M Calvi20,72, L Cassina20,72, C Gotti20,72, B Khanji20,38,72, M Kucharczyk20,26,72, C Matteuzzi20, J Fu21,38, A Geraci21,78, N Neri21, F Palombo21,85, S Amerio22, G Collazuol22, S Gallorini22,38, A Gianelle22, D Lucchesi22,81, A Lupato22, M Morandin22, M Rotondo22, L Sestini22, G Simi22, R Stroili22, F Bedeschi23, R Cenci23,77, S Leo23, P Marino23,77, M.J Morello23,77, G Punzi23,87, S Stracka23,77, J Walsh23, G Carboni24,75, E Furfaro24,75, E Santovetti24,75, A Satta24, A.A Alves Jr25,38, G Auriemma25,70, V Bocci25, G Martellotti25, G Penso25,86, D Pinci25, R Santacesaria25, C Satriano25,70, A Sciubba25,86, A Dziurda26, W Kucewicz26,80, T Lesiak26, B Rachwal26, M Witek26, M Firlej27, T Fiutowski27, M Idzik27, P Morawski27, G2015 J Moron27, A Oblakowska-Mucha27,38, K Swientek27, T Szumlak27, V Batozskaya28, K Klimaszewski28, K Kurek28, M Szczekowski28, A Ukleja28, W Wislicki28, L Cojocariu29, L Giubega29, A Grecu29, F Maciuc29, M Orlandea29, B Popovici29, S Stoica29, M Straticiuc29, G Alkhazov30, N Bondar30,38, A Dzyuba30, O Maev30, N Sagidova30, Y Shcheglov30, A Vorobyev30, S Belogurov31, I Belyaev31, V Egorychev31, D Golubkov31, T Kvaratskheliya31, I.V Machikhiliyan31, I Polyakov31, D Savrina31,32, A Semennikov31, A Zhokhov31, A Berezhnoy32, M Korolev32, A Leflat32, N Nikitin32, S Filippov33, E Gushchin33, L Kravchuk33, A Bondar34, S Eidelman34, P Krokovny34, V Kudryavtsev34, L Shekhtman34, V Vorobyev34, A Artamonov35, K Belous35, R Dzhelyadin35, Yu Guz35,38, A Novoselov35, V Obraztsov35, A Popov35, V Romanovsky35, M Shapkin35, O Stenyakin35, O Yushchenko35, A Badalov36, M Calvo Gomez36,73, L Garrido36, D Gascon36, R Graciani Diaz36, E Grauge´s36, C Marin Benito36, E Picatoste Olloqui36, V Rives Molina36, H Ruiz36, X Vilasis-Cardona36,73, B Adeva37, P Alvarez Cartelle37, A Dosil Sua´rez37, V Fernandez Albor37, A Gallas Torreira37, J Garcı´a Pardin˜as37, J.A Hernando Morata37, M Plo Casasus37, A Romero Vidal37, J.J Saborido Silva37, B Sanmartin Sedes37, C Santamarina Rios37, P Vazquez Regueiro37, C Va´zquez Sierra37, M Vieites Diaz37, F Alessio38, F Archilli38, C Barschel38, S Benson38, J Buytaert38, D Campora Perez38, L Castillo Garcia38, M Cattaneo38, Ph Charpentier38, X Cid Vidal38, M Clemencic38, J Closier38, V Coco38, P Collins38, G Corti38, B Couturier38, C D’Ambrosio38, F Dettori38, A Di Canto38, H Dijkstra38, P Durante38, M Ferro-Luzzi38, R Forty38, M Frank38, C Frei38, C Gaspar38, V.V Gligorov38, L.A Granado Cardoso38, T Gys38, C Haen38, J He38, T Head38, E van Herwijnen38, R Jacobsson38, D Johnson38, C Joram38, B Jost38, M Karacson38, T.M Karbach38, D Lacarrere38, B Langhans38, R Lindner38, C Linn38, S Lohn38, A Mapelli38, R Matev38, Z Mathe38, S Neubert38, N Neufeld38, A Otto38, J Panman38, M Pepe Altarelli38, N Rauschmayr38, M Rihl38, S Roiser38, T Ruf38, H Schindler38, B Schmidt38, A Schopper38, R Schwemmer38, S Sridharan38, F Stagni38, V.K Subbiah38, F Teubert38, E Thomas38, D Tonelli38, A Trisovic38, M Ubeda Garcia38, J Wicht38, K Wyllie38, V Battista39, A Bay39, F Blanc39, M Dorigo39, F Dupertuis39, C Fitzpatrick39, S Gianı`39, G Haefeli39, P Jaton39, C Khurewathanakul39, I Komarov39, V.N La Thi39, N Lopez-March39, R Maărki39, M Martinelli39, B Muster39, T Nakada39, A.D Nguyen39, T.D Nguyen39, C Nguyen-Mau39,83, J Prisciandaro39, A Puig Navarro39, B Rakotomiaramanana39, J Rouvinet39, O Schneider39, F Soomro39, P Szczypka39,38, M Tobin39, S Tourneur39, M.T Tran39, G Veneziano39, Z Xu39, J Anderson40, R Bernet40, E Bowen40, A Bursche40, N Chiapolini40, M Chrzaszcz40,26, Ch Elsasser40, E Graverini40, F Lionetto40, P Lowdon40, K Muăller40, N Serra40, O Steinkamp40, B Storaci40, U Straumann40, M Tresch40, A Vollhardt40, R Aaij41, S Ali41, M van Beuzekom41, P.N.Y David41, K De Bruyn41, C Farinelli41, V Heijne41, W Hulsbergen41, E Jans41, P Koppenburg41,38, A Kozlinskiy41, J van Leerdam41, M Merk41, S Oggero41, A Pellegrino41, H Snoek41, J van Tilburg41, P Tsopelas41, N Tuning41, J.A de Vries41, T Ketel42, R.F Koopman42, R.W Lambert42, D Martinez Santos42,38, G Raven42, M Schiller42, V Syropoulos42, S Tolk42, A Dovbnya43, S Kandybei43, I Raniuk43, O Okhrimenko44, V Pugatch44, S Bifani45, N Farley45, P Griffith45, I.R Kenyon45, C Lazzeroni45, A Mazurov45, J McCarthy45, L Pescatore45, N.K Watson45, M.P Williams45, M Adinolfi46, J Benton46, N.H Brook46, A Cook46, M Coombes46, J Dalseno46, T Hampson46, S.T Harnew46, P Naik46, E Price46, C Prouve46, J.H Rademacker46, S Richards46, D.M Saunders46, N Skidmore46, D Souza46, J.J Velthuis46, D Voong46, W Barter47, M.-O Bettler47, H.V Cliff47, H.-M Evans47, J Garra Tico47, V Gibson47, S Gregson47, S.C Haines47, C.R Jones47, M Sirendi47, J Smith47, D.R Ward47, S.A Wotton47, S Wright47, J.J Back48, T Blake48, D.C Craik48, A.C Crocombe48, D Dossett48, T Gershon48, M Kreps48, C Langenbruch48, T Latham48, D.P O’Hanlon48, T Pilarˇ48, A Poluektov48,34, M.M Reid48, R Silva Coutinho48, C Wallace48, M Whitehead48, S Easo49,38, R Nandakumar49, A Papanestis49,38, S Ricciardi49, F.F Wilson49, L Carson50, P.E.L Clarke50, G.A Cowan50, S Eisenhardt50, D Ferguson50, D Lambert50, H Luo50, A.-B Morris50, F Muheim50, M Needham50, S Playfer50, M Alexander51, J Beddow51, C.-T Dean51, L Eklund51, D Hynds51, S Karodia51, I Longstaff51, S Ogilvy51, M Pappagallo51, P Sail51, I Skillicorn51, F.J.P Soler51, P Spradlin51, A Affolder52, T.J.V Bowcock52, H Brown52, G Casse52, S Donleavy52, K Dreimanis52, S Farry52, R Fay52, K Hennessy52, D Hutchcroft52, M Liles52, B McSkelly52, G.D Patel52, J.D Price52, A Pritchard52, K Rinnert52, T Shears52, N.A Smith52, G Ciezarek53, S Cunliffe53, R Currie53, U Egede53, P Fol53, A Golutvin53,31,38, S Hall53, M McCann53, P Owen53, M Patel53, K Petridis53, F Redi53, I Sepp53, E Smith53, W Sutcliffe53, D Websdale53, R.B Appleby54, R.J Barlow54, T Bird54, P.M Bjørnstad54, S Borghi54, D Brett54, J Brodzicka54, L Capriotti54, S Chen54, S De Capua54, G Dujany54, M Gersabeck54, J Harrison54, C Hombach54, S Klaver54, G Lafferty54, A McNab54, C Parkes54, A Pearce54, S Reichert54, E Rodrigues54, P Rodriguez Perez54, M Smith54, S.-F Cheung55, D Derkach55, T Evans55, R Gauld55, E Greening55, N Harnew55, D Hill55, P Hunt55, N Hussain55, J Jalocha55, M John55, O Lupton55, S Malde55, E Smith55, S Stevenson55, C Thomas55, S ToppJoergensen55, N Torr55, G Wilkinson55,38, I Counts56, P Ilten56, M Williams56, R Andreassen57, A Davis57, W De Silva57, B Meadows57, M.D Sokoloff57, L Sun57, J Todd57, J.E Andrews58, B Hamilton58, A Jawahery58, J Wimberley58, M Artuso59, S Blusk59, A Borgia59, T Britton59, S Ely59, P Gandini59, J Garofoli59, B Gui59, C Hadjivasiliou59, N Jurik59, M Kelsey59, R Mountain59, B.K Pal59, T Skwarnicki59, S Stone59, J Wang59, Z Xing59, L Zhang59, C Baesso60, M Cruz Torres60, C Goăbel60, J Molina Rodriguez60, Y Xie61, D.A Milanes62, O Gruănberg63, M Heò63, C Voò63, R Waldi63, T Likhomanenko64, A Malinin64, V Shevchenko64, A Ustyuzhanin64, F Martinez Vidal65, A Oyanguren65, P Ruiz Valls65, C Sanchez Mayordomo65, C.J.G Onderwater66, H.W Wilschut66 & E Pesen67 Primary affiliations Centro Brasileiro de Pesquisas Fı´sicas (CBPF), Rio de Janeiro, Brazil 2Universidade Federal Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil 3Center for High Energy Physics, Tsinghua University, Beijing, China 4LAPP, Universite´ de Savoie, CNRS/IN2P3, AnnecyLe-Vieux, France 5Clermont Universite´, Universite´ Blaise Pascal, CNRS/IN2P3, LPC, Clermont-Ferrand, France 6CPPM, Aix-Marseille Universite´, CNRS/IN2P3, Marseille, Macmillan Publishers Limited All rights reserved LETTER RESEARCH France 7LAL, Universite´ Paris-Sud, CNRS/IN2P3, Orsay, France 8LPNHE, Universite´ Pierre et Marie Curie, Universite´ Paris Diderot, CNRS/IN2P3, Paris, France 9Fakultaăt Physik, Technische Universitaăt Dortmund, Dortmund, Germany 10Max-Planck-Institut fuăr Kernphysik (MPIK), Heidelberg, Germany 11Physikalisches Institut, Ruprecht-KarlsUniversitaăt Heidelberg, Heidelberg, Germany 12School of Physics, University College Dublin, Dublin, Ireland 13Sezione INFN di Bari, Bari, Italy 14Sezione INFN di Bologna, Bologna, Italy 15Sezione INFN di Cagliari, Cagliari, Italy 16Sezione INFN di Ferrara, Ferrara, Italy 17Sezione INFN di Firenze, Firenze, Italy 18Laboratori Nazionali dell’INFN di Frascati, Frascati, Italy 19Sezione INFN di Genova, Genova, Italy 20Sezione INFN di Milano Bicocca, Milano, Italy 21Sezione INFN di Milano, Milano, Italy 22Sezione INFN di Padova, Padova, Italy 23Sezione INFN di Pisa, Pisa, Italy 24Sezione INFN di Roma Tor Vergata, Roma, Italy 25Sezione INFN di Roma La Sapienza, Roma, Italy 26Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences, Krako´w, Poland 27AGH - University of Science and Technology, Faculty of Physics and Applied Computer Science, Krako´w, Poland 28National Center for Nuclear Research (NCBJ), Warsaw, Poland 29Horia Hulubei National Institute of Physics and Nuclear Engineering, Bucharest-Magurele, Romania 30Petersburg Nuclear Physics Institute (PNPI), Gatchina, Russia 31Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia 32Institute of Nuclear Physics, Moscow State University (SINP MSU), Moscow, Russia 33Institute for Nuclear Research of the Russian Academy of Sciences (INR RAN), Moscow, Russia 34Budker Institute of Nuclear Physics (SB RAS) and Novosibirsk State University, Novosibirsk, Russia 35Institute for High Energy Physics (IHEP), Protvino, Russia 36Universitat de Barcelona, Barcelona, Spain 37Universidad de Santiago de Compostela, Santiago de Compostela, Spain 38European Organization for Nuclear Research (CERN), Geneva, Switzerland 39Ecole Polytechnique Fe´de´rale de Lausanne (EPFL), Lausanne, Switzerland 40Physik-Institut, Universitaăt Zuărich, Zuărich, Switzerland 41 Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands 42 Nikhef National Institute for Subatomic Physics and VU University Amsterdam, Amsterdam, The Netherlands 43NSC Kharkiv Institute of Physics and Technology (NSC KIPT), Kharkiv, Ukraine 44Institute for Nuclear Research of the National Academy of Sciences (KINR), Kyiv, Ukraine 45University of Birmingham, Birmingham, United Kingdom 46H.H Wills Physics Laboratory, University of Bristol, Bristol, United Kingdom 47 Cavendish Laboratory, University of Cambridge, Cambridge, United Kingdom 48 Department of Physics, University of Warwick, Coventry, United Kingdom 49STFC Rutherford Appleton Laboratory, Didcot, United Kingdom 50School of Physics and Astronomy, University of Edinburgh, Edinburgh, United Kingdom 51School of Physics and Astronomy, University of Glasgow, Glasgow, United Kingdom 52Oliver Lodge G2015 Laboratory, University of Liverpool, Liverpool, United Kingdom 53Imperial College London, London, United Kingdom 54School of Physics and Astronomy, University of Manchester, Manchester, United Kingdom 55Department of Physics, University of Oxford, Oxford, United Kingdom 56Massachusetts Institute of Technology, Cambridge, MA, United States 57University of Cincinnati, Cincinnati, OH, United States 58University of Maryland, College Park, MD, United States 59Syracuse University, Syracuse, NY, United States 60Pontifı´cia Universidade Cato´lica Rio de Janeiro (PUC-Rio), Rio de Janeiro, Brazil; Universidade Federal Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil 61Institute of Particle Physics, Central China Normal University, Wuhan, Hubei, China; Center for High Energy Physics, Tsinghua University, Beijing, China 62Departamento de Fisica, Universidad Nacional de Colombia, Bogota, Colombia; LPNHE, Universite´ Pierre et Marie Curie, Universite´ Paris Diderot, CNRS/IN2P3, Paris, France 63Institut fuăr Physik, Universitaăt Rostock, Rostock, Germany; Physikalisches Institut, Ruprecht-Karls-Universitaăt Heidelberg, Heidelberg, Germany 64National Research Centre Kurchatov Institute, Moscow, Russia; Institute of Theoretical and Experimental Physics (ITEP), Moscow, Russia 65 Instituto de Fisica Corpuscular (IFIC), Universitat de Valencia-CSIC, Valencia, Spain; Universitat de Barcelona, Barcelona, Spain 66Van Swinderen Institute, University of Groningen, Groningen, The Netherlands; Nikhef National Institute for Subatomic Physics, Amsterdam, The Netherlands 67Celal Bayar University, Manisa, Turkey; European Organization for Nuclear Research (CERN), Geneva, Switzerland Secondary affiliations 68 Universita` di Firenze, Firenze, Italy 69Universita` di Ferrara, Ferrara, Italy 70Universita` della Basilicata, Potenza, Italy 71Universita` di Modena e Reggio Emilia, Modena, Italy 72 Universita` di Milano Bicocca, Milano, Italy 73LIFAELS, La Salle, Universitat Ramon Llull, Barcelona, Spain 74Universita` di Bologna, Bologna, Italy 75Universita` di Roma Tor Vergata, Roma, Italy 76Universita` di Genova, Genova, Italy 77Scuola Normale Superiore, Pisa, Italy 78Politecnico di Milano, Milano, Italy 79Universidade Federal Triaˆngulo Mineiro (UFTM), Uberaba-MG, Brazil 80AGH - University of Science and Technology, Faculty of Computer Science, Electronics and Telecommunications, Krako´w, Poland 81 Universita` di Padova, Padova, Italy 82Universita` di Cagliari, Cagliari, Italy 83Hanoi University of Science, Hanoi, Viet Nam 84Universita` di Bari, Bari, Italy 85Universita` degli Studi di Milano, Milano, Italy 86Universita` di Roma La Sapienza, Roma, Italy 87Universita` di Pisa, Pisa, Italy 88Universita` di Urbino, Urbino, Italy 89P.N Lebedev Physical Institute, Russian Academy of Science (LPI RAS), Moscow, Russia Macmillan Publishers Limited All rights reserved RESEARCH LETTER Extended Data Figure | Distribution of the dimuon invariant mass mm1m2 in each of the 20 categories Superimposed on the data points in black are the combined fit (solid blue) and its components: the B0s (yellow shaded) and B0 (light-blue shaded) signal components; the combinatorial background (dashdotted green); the sum of the semi-leptonic backgrounds (dotted salmon); and the peaking backgrounds (dashed violet) The categories are defined by the G2015 range of BDT values for LHCb, and for CMS, by centre-of-mass energy, by the region of the detector in which the muons are detected, and by the range of BDT values Categories for which both muons are detected in the central region of the CMS detector are denoted with CR, those for which at least one muon was detected into the forward region with FR Macmillan Publishers Limited All rights reserved LETTER RESEARCH Extended Data Figure | Distribution of the dimuon invariant mass mm1m2 for the best six categories Categories are ranked according to values of S/(S B) where S and B are the numbers of signal events expected assuming the SM rates and background events under the B0s peak for a given category, respectively The mass distribution for the six highest-ranking categories, three G2015 per experiment, is shown Superimposed on the data points in black are the combined full fit (solid blue) and its components: the B0s (yellow shaded) and B0 (light-blue shaded) signal components; the combinatorial background (dash-dotted green); the sum of the semi-leptonic backgrounds (dotted salmon); and the peaking backgrounds (dashed violet) Macmillan Publishers Limited All rights reserved RESEARCH LETTER Extended Data Figure | Schematic of the CMS detector and event display for a candidate Bs0 Rm1m2 decay at CMS a, The CMS detector and its components; see ref 20 for details b, A candidate B0s ?mz m{ decay produced G2015 in proton–proton collisions at TeV in 2012 and recorded in the CMS detector The red arched curves represent the trajectories of the muons from the B0s decay candidate Macmillan Publishers Limited All rights reserved LETTER RESEARCH Extended Data Figure | Schematic of the LHCb detector and event display for a candidate Bs0 Rm1m2 decay at LHCb a, The LHCb detector and its components; see ref 21 for details b, A candidate B0s ?mz m{ decay produced in proton–proton collisions at TeV in 2011 and recorded in the LHCb G2015 detector The proton–proton collision occurs on the left-hand side, at the origin of the trajectories depicted with the orange curves The red curves represent the trajectories of the muons from the B0s candidate decay Macmillan Publishers Limited All rights reserved − CL RESEARCH LETTER CMS and LHCb (LHC run I) SM 10−1 10−2 10−3 0.2 0.4 0.6 0.8 B(B → μ + μ −) [10−9] Extended Data Figure | Confidence level as a function of the B(B0R m1m2) hypothesis The value of CL, where CL is the confidence level obtained with the Feldman–Cousins procedure, as a function of B(B0 R m1m2) is shown in logarithmic scale The points mark the computed CL values and the curve is their spline interpolation The dark and light (cyan) areas define the two-sided 61s and 62s confidence intervals for the branching fraction, while G2015 the dashed horizontal line defines the confidence level for the 3s one-sided interval The dashed (grey) curve shows the CL values computed from the one-dimensional 22DlnL test statistic using Wilks’ theorem Deviations between these confidence level values and those from the Feldman–Cousins procedure30 illustrate the degree of approximation implied by the asymptotic assumptions inherent to Wilks’ theorem29 Macmillan Publishers Limited All rights reserved LETTER RESEARCH Extended Data Figure | Likelihood contours for the ratios of the0 branching fractions with respect to their SM prediction, in the S BSM versus Bs0 S SM plane a, The (black) cross marks the central value returned by the fit The SM point is shown as the (red) square located, by construction, B0s ~1 Each contour encloses a region approximately corresponding at S BSM ~S SM to the reported confidence level The SM branching fractions are assumed G2015 uncorrelated to each other, and their uncertainties are accounted for in0 the Bs and likelihood contours b, c, Variations of the test statistic 22DlnL for S SM B0 S SM are shown in b and c, respectively The SM is represented by the (red) vertical lines The dark and light (cyan) areas define the 61s and 62s confidence intervals, respectively Macmillan Publishers Limited All rights reserved Limit (90% CL) or BF measurement RESEARCH LETTER −8 10 10− −9 10 −5 10 − 10 10 10− 2012 2013 2014 10− 10− CLEO ARGUS UA1 CDF L3 D0 10− − 10 10 1985 Belle BaBar LHCb CMS ATLAS CMS+LHCb 1990 1995 SM: Bs → μ+μ− SM: B0 → μ+μ− 2000 2005 2010 2015 Year Extended Data Figure | Search for the Bs0 Rm1m2 and B0Rm1m2 decays, reported by 11 experiments spanning more than three decades, and by the present results Markers without error bars denote upper limits on the branching fractions at 90% confidence level, while measurements are denoted with error bars delimiting 68% confidence intervals The solid horizontal lines G2015 represent the SM predictions for the B0s ?mz m{ and B0 R m1m2 branching fractions1; the blue (red) lines and markers relate to the B0s ?mz m{ (B0 R m1m2) decay Data (see key) are from refs 17, 18, 31–60; for details see Methods Inset, magnified view of the last period in time Macmillan Publishers Limited All rights reserved ... exploit fully the statistical power of the data and to account for the main correlations between them The data correspond to total integrated luminosities of 25 fb21 and fb21 for the CMS and LHCb experiments,... samples from data The LHCb analysis is designed to minimize the impact of discrepancies between simulations and data The mass resolution is measured with data The distribution of the BDT for the. .. compatible with the SM at the 2.3s level The one-dimensional likelihood scan for this parameter is shown in Fig The combined analysis of data from CMS and LHCb, taking advantage of their full statistical