The BABAR physics book physics at an asymmetric b factory

SLAC-R-504 The BABAR Physics Book: Physics at an Asymmetric B Factory   This book presents the results of a year-long workshop devoted to a review of the physics opportunities of the BABAR experiment at the PEP-II B Factory, at the Stanford Linear Accelerator Center Laboratory * Work supported in part by US Department of Energy contract DE-AC02-76SF00515 SLAC National Accelerator Laboratory, Menlo Park, CA 94025 This page was intentionally left blank The BABAR Collaboration LAPP Annecy, Annecy-le-Vieux, France D Boutigny, I De Bonis, Y Karyotakis, R Lafaye, V Tisserand INFN Sezione di Bari, Bari, Italy C Evangelista, A Palano Beijing Glass Research Institute, Beijing, China G Chen, S Ren, O Wen, H Yu, F Zhang, Y Zheng Institute of High Energy Physics, Beijing, China G Chen, Y Guo, H Lan, H Mao, N Qi, P P Xie, W G Yan, C Zhang, W Zhao, Y Zhu University of Bergen, Bergen, Norway A Borgland, G Eigen, B Stugu Ruhr-Universităat Bochum, Bochum, Germany H Koch, M Kunze, B Lewandowski, K Peters, H Schmăucker, M Steinke University of Bristol, Bristol, UK J C Andress, N Dyce, B Foster, A Mass, J McFall University of British Columbia, Vancouver, British Columbia, Canada C Hearty, M H Kelsey, J McKenna Brunel University, London, UK B Camanzi, T J Champion, A K McKemey, J Tinslay Budker Institute of Nuclear Physics, Novosibirsk, Russia V E Blinov, A D Bukin, A R Buzykaev, S F Ganzhur, V N Ivanchenko, A A Korol, E A Kravchenko, A P Onuchin, S I Serednyakov, Yu I Skovpen, V I Telnov California Institute of Technology, Pasadena, California, USA E Chen, G P Dubois-Felsmann, D G Hitlin, Y G Kolomensky, S Metzler, B B Naranjo, F C Porter, A Ryd, A Samuel, M Weaver, S Yang, R Zhu University of California, Irvine, Irvine, California, USA A Lankford, M Mandelkern, D.P Stoker, G Zioulas University of California, Los Angeles, Los Angeles, California, USA C Buchanan, S Chun iv University of California, San Diego, La Jolla, California, USA J G Branson, R Faccini, C Hast, D B MacFarlane, E Potter, S Rahatlou, G Raven, V Sharma, F Wilson University of California, Santa Barbara, Santa Barbara, California, USA D.A Bauer, C Campagnari, A Eppich, P Hart, N Kuznetsova, O Long, A Lu, J.D Richman, M Witherell, S Yellin University of California, Santa Cruz, Santa Cruz, California, USA J Beringer, D E Dorfan, A M Eisner, A Frey, A A Grillo, C A Heusch, R P Johnson, W S Lockman, M Munson, T Pulliam, H Sadrozinski, T Schalk, B A Schumm, A Seiden, M Turri University of Cincinnati, Cincinnati, Ohio, USA S Devmal, T Geld, B T Meadows, D Renner, M D Sokoloff Colorado State University, Fort Collins, Colorado, USA J L Harton, R Malchow, A Soffer, W H Toki, R J Wilson, W Yang University of Colorado, Boulder, Colorado, USA S Fahey, W T Ford, F Gaede, K M Hall, T L Hall, D R Johnson, H Krieg, U Nauenberg, P Rankin, J Roy, S Sen, J G Smith, D L Wagner, M Zhao Technische Universităat Dresden, Dresden, Germany T Brandt, J Brose, M L Kocian, R Măuller-Pfefferkorn, K R Schubert, R Schwierz, B Spaan, R Waldi University of Edinburgh, Edinburgh, UK R Bernet, P Clark, S Gowdy, S Playfer INFN Sezione di Ferrara, Ferrara, Italy S Dittongo, M Folegani, L Piemontese INFN Laboratori Nazionali di Frascati, Frascati, Italy F Anulli, A Asmone, R Baldini-Ferroli, A Calcaterra, D Falciai, G Finocchiaro, I M Peruzzi, M Piccolo, R de Sangro, Z Yu, A Zallo INFN Sezione di Genova, Genova, Italy A Buzzo, R Contri, G Crosetti, M Lo Vetere, M Macri, M R Monge, M Pallavicini, R Parodi, C Patrignani, M G Pia, E Robutti, A Santroni Imperial College, London, UK P D Dauncey, R Martin, J.A Nash, P Sanders, D Smith, P Strother Iowa State University, Ames, Iowa, USA H B Crawley, A Firestone, J Lamsa, W T Meyer, E I Rosenberg R EPORT OF THE BABAR P HYSICS WORKSHOP v University of Iowa, Iowa City, Iowa, USA R Bartoldus, T Dignan, R Hamilton, U Mallik Lawrence Berkeley National Laboratory, Berkeley, California, USA B Abbott, G S Abrams, A Breon, D N Brown, R N Cahn, A R Clark, C T Day, Q Fan, R G Jacobsen, R W Kadel, J Kadyk, R Kapur, A Karcher, R Kerth, S Kluth, J F Kral, C LeClerc, M Levi, D Li, T Liu, G Lynch, M Marino, A Meyer, A Mokhtarani, P J Oddone, J Ohnemus, S J Patton, M Pripstein, D R Quarrie, N A Roe, A Romosan, M Ronan, V G Shelkov, A V Telnov, W A Wenzel Lawrence Livermore National Laboratory, Livermore, California, USA P D Barnes, R M Bionta, D Fujino, M N Kreisler, M Mugge, X Shi, K A Van Bibber, D Wright, C R Wuest University of Liverpool, Liverpool, UK M Carroll, G Dahlinger, J R Fry, E Gabathuler, R Gamet, M George, S McMahon, C Touramanis University of Louisville, Louisville, Kentucky D Brown, C Davis, J Pavlovich, A Trunov University of Manchester, Manchester, UK J Allison, R Barlow, A Khan, G Lafferty, A McNab, N Savvas, A Walkden, J Weatherall University of Maryland, College Park, Maryland, USA C Dallapiccola, D Fong, A Jawahery, D A Roberts, A Skuja Massachusetts Institute of Technology, Cambridge, Massachusetts, USA R F Cowan, R K Yamamoto University of Massachusetts, Amherst, Amherst, Massachusetts, USA K Baird, G Blaylock, J Button-Shafer, K Flood, S S Hertzbach, R Kofler, C S Lin, J Wittlin McGill University, Montr´eal, Quebec, Canada P Bloom, M Milek, P M Patel, J Trischuk INFN Sezione di Milano, Milano, Italy A Forti, F Lanni, F Palombo, V Pozdnyakov University of Mississippi, University, Mississippi, USA J M Bauer, L Cremaldi, V Eschenburg, R Kroeger, J Reidy, D Sanders, J Secrest, D Summers Universit´e of Montr´eal, Montr´eal, Quebec, Canada A Hasan, J Martin, R Seitz, P Taras, A Woch, V Zacek R EPORT OF THE BABAR P HYSICS WORKSHOP vi Mount Holyoke College, South Hadley, Massachusetts, USA H Nicholson, C S Sutton INFN Sezione di Napoli, Napoli, Italy G P Carlino, N Cavallo, G De Nardo, F Fabozzi, C Gatto, L Lista, P Paolucci, D Piccolo, C Sciacca Northern Kentucky University, Highland Heights, Kentucky, USA M Falbo-Kenkel University of Notre Dame, Notre Dame, Indiana J Bishop, N M Cason, A Garcia, J M LoSecco, W D Shephard Oak Ridge National Laboratory, Oak Ridge, Tennessee, USA R Alsmiller, T A Gabriel LAL Orsay, Orsay, France M Benkebil, G Grosdidier, A Hoecker, V Lepeltier, A Lutz, S Plaszczynski, M.-H Schune, A Valassi, G Wormser, F Zomer INFN Sezione di Padova, Padova, Italy F Dal Corso, F Galeazzi, M Morandin, M Posocco, R Stroili, C Voci Ecole Polytechnique Palaiseau, LPNHE, Palaiseau, France L Behr, G R Bonneaud, E Roussot, C Thiebaux, G Vasileiadis, M Verderi LPNHE Universit´e de Paris VI et VII, Paris, France M Benayoun, H Briand, J Chauveau, P David, C de la Vaissi`ere, L Del Buono, O Hamon, F Le Diberder, Ph Leruste, J Lory, L Martin, J.-L Narjoux, N Regnault, L Roos, S Versill´e INFN Sezione di Pavia, Pavia, Italy A Leona, A Leona, E Mandelli, P F Manfredi, A Perazzo, L Ratti, V Re, V Speziali University of Pennsylvania, Philadelphia, Pennsylvania, USA C Cretsinger, E Frank, L Gladney, V Suraiya INFN Sezione di Pisa, Pisa, Italy C Angelini, G Batignani, S Bettarini, M Bondioli, G Calderini, M Carpinelli, F Costantini, F Dutra, F Forti, M A Giorgi, A Lusiani, S Mettarini, M Morganti, F Morsani, M Rama, G Rizzo, G Simi, G Triggiani, R Vitale Prairie View A& M University, Prairie View, Texas, USA M Haire, D Judd, K Paick, D Wagoner Princeton University, Princeton, New Jersey, USA J Albert, C Lu, K T McDonald, V Miftakov, S F Schaffner, A J S Smith, A Tumanov, E W Varnes R EPORT OF THE BABAR P HYSICS WORKSHOP vii Queen Mary & Westfield College, London, UK J J Back, P F Harrison, A J Martin University di Roma ‘La Sapienza’ and INFN Sezione di Roma, Rome, Italy G Cavoto, F Ferrarotto, F Ferroni, E Lamanna, S Mazzoni, S Morganti, G Piredda, M Rotondo Royal Holloway & Bedford New College, London, UK M G Green, I Scott, E Tetteh-Lartey Rutgers University, Rutgers, New Jersey, USA P F Jacques, M S Kalelkar, G Mancinelli, R J Plano Rutherford Appleton Laboratory, Chilton, Didcot, UK T Adye, U Egede, B Franek, N I Geddes, G P Gopal CEA, DAPNIA, CE-Saclay, Gif-sur-Yvette, France R Aleksan, G De Domenico, S Emery, A Gaidot, G Hamel de Monchenault, A de Lesquen, G.W London, B Mayer, A Salnikov, G H Vasseur, C Yeche, M Zito Shanghai Institute of Ceramics (SICCAS), Shanghai, China D Yan, Z Yin University of South Carolina, Columbia, South Carolina, USA N Copty, M Purohit Stanford Linear Accelerator Center, Stanford, California, USA I Adam, P L Anthony, D Aston, A Bajic, E Bloom, A M Boyarski, F Bulos, J Cohen-Tanugi, M R Convery, D P Coupal, D H Coward, N De Groot, J Dorfan, M Doser, W Dunwoodie, T Glanzman, G L Godfrey, J L Hewett, T Himel, W R Innes, C P Jessop, L Keller, P C Kim, P F Kunz, W G J Langeveld, D W G S Leith, K Lingel, V Luth, H L Lynch, G Manzin, H Marsiske, T.S Mattison, R Messner, K Moffeit, M Morii, R Mount, D.R Muller, C.P 0’Grady, T.J Pavel, R Pitthan, B N Ratcliff, L S Rochester, V Savinov, R H Schindler, J Schwiening, G Sciolla, V V Serbo, A Snyder, A Stahl, D Su, M K Sullivan, M Talby, H A Tanaka, J Va’vra, S R Wagner, A Weinstein, W J Wisniewski, C C Young Stanford University, Stanford, California, USA P Burchat, C H Cheng, D Kirkby, T I Meyer, E Nehrlich, C Roat, R Zaliznyak University of Texas, Dallas, Dallas, Texas, USA J H Cooke III, J M Izen, X C Lou, M Turcotte INFN Sezione di Torino, Torino, Italy F Bianchi, B DiGirolamo, D Gamba, P Grosso, A Romero, A Smol, A Vitelli, D Zanin R EPORT OF THE BABAR P HYSICS WORKSHOP viii INFN Sezione di Trieste, Trieste, Italy L Bosisio, G Castelli, G Della Ricca, L Lanceri, G Musolino, P Poropat, M Prest, E Vallazza, G Vuagnin TRIUMF, Vancouver, British Columbia, Canada R Henderson Vanderbilt University, Nashville, Tennessee, USA R S Panvini University of Victoria, Victoria, British Columbia, Canada A DeSilva, R V Kowalewski, J M Roney University of Wisconsin, Madison, Madison, Wisconsin, USA H Band, E Charles, S Dasu, P Elmer, J Johnson, J Nielsen, W Orejudos, Y Pan, R Prepost, I Scott, J Walsh, S L Wu, H Zobernig R EPORT OF THE BABAR P HYSICS WORKSHOP Participating Theorists D Atwood, Iowa State University; P Ball, European Laboratory for Particle Physics, CERN; I Bigi, University of Notre Dame; F M Borzumati, Universităat Zăurich; C G Boyd, Carnegie Mellon University; G C Branco, Instituto Superior T´ecnico, Lisbon; V M Braun, Nordisk Institut for Teoretisk Fysik, NORDITA; F Buccella, INFN Sezione di Naples; G Buchalla, European Laboratory for Particle Physics, CERN; G Burdman, University of Wisconsin; R N Cahn, Lawrence Berkeley National Laboratory; J Charles, Laboratoire de Physique Th´eorique et Hautes Energies, Orsay; M Ciuchini, INFN Sezione di Rome; F E Close, Rutherford Appelton Laboratory; P Colangelo, INFN Sezione di Bari; F De Fazio, INFN Sezione di Bari; A S Dighe, International Centre for Theoretical Physics, Trieste; I Dunietz, Fermi National Accelerator Laboratory; A F Falk, Johns Hopkins University; R Fleischer, European Laboratory for Particle Physics, CERN; J M Flynn, University of Southampton; M C Gonzalez-Garcia, Universidad de Val`encia; B Grinstein, University of California, San Diego; Y Grossman, Stanford Linear Accelerator Center; D Guetta, INFN Sezione di Bologna; J L Hewett, Stanford Linear Accelerator Center; G Isidori, Laboratori Nazionali de Frascati; A L Kagan, University of Cincinnati; Y Y Keum, APCPT, Seoul National University; A Khodjamirian, Universităat Wăurzburg; J H Kăuhn, Universităat Karlsruhe; A Le Yaouanc, Laboratoire de Physique Th´eorique et Hautes Energies, Orsay; L Lellouch, European Laboratory for Particle Physics, CERN; Z Ligeti, University of California, San Diego; D London, Universit´e de Montr´eal; M Lusignoli, INFN Sezione di Rome; T Mannel, Universităat Karlsruhe, G Martinelli, INFN Sezione di Rome; A Masiero, INFN Sezione di Padova; B Mayer, Centre d’Etudes Nucl´eaires de Saclay; G Michelon, International Centre for Theoretical Physics, Trieste; E Mirkes, Universităat Karlsruhe; E Nardi, Antioquia University; M Neubert, European Laboratory for Particle Physics, CERN; U Nierste, DESY Deutsches Elektronen-Synchrotron; Y Nir, The Weizmann Institute of Science; L Oliver, Laboratoire de Physique Th´eorique et Hautes Energies, Orsay; N Paver, INFN Sezione di Trieste; R D Peccei, University of California, Los Angeles; O Pene, Laboratoire de Physique Th´eorique et Hautes Energies, Orsay; A A Petrov, Johns Hopkins University; A Pich, Universidad de Val`encia; A Pugliese, INFN Sezione di Rome; H R Quinn, Stanford Linear Accelerator Center; L Reina, University of Wisconsin; G Ricciardi, INFN Sezione di Naples; T G Rizzo, Stanford Linear Accelerator Center; R Răuckl, Universităat Wăurzburg; C T Sachrajda, University of Southampton; D Silverman, University of California, Irvine; L Silvestrini, Universit`a di Roma; A Soni, Brookhaven National Laboratory; B F.L Ward, University of Tennessee; J D Wells, Stanford Linear Accelerator Center; M B Wise, California Institute of Technology; M P Worah,Stanford Linear Accelerator Center; D Wyler, Universităat Zăurich x R EPORT OF THE BABAR P HYSICS WORKSHOP 682 Hadronic f g B Meson Decays L where denotes the time-ordered product and W the effective weak Lagrangian at the parton level For a sufficiently high-energy release in the decay the nonlocal operator product in Eq (10.110) can, through an operator product expansion (OPE), be expressed as an infinite sum of local operators Oi of increasing dimension with coefficients c~i containing higher and higher powers of 1=mQ ; a short-distance mass must be used here for the heavy quarks The width for a hadron HQ containing the heavy quark, Q, is then obtained by taking the expectation value of T^ for the state HQ : X hHQjT^jHQi ,HQ ! f  = G2F jCKM j2 c~if  hHQjOijHQi ; (10.111) i where CKM denotes the appropriate CKM matrix elements Through order following form: 1=m3Q it takes the " G2F m5Q ,HQ ! f  = 1923 jCKM j cf3 hHQjQQjHQi + cf5 hHQjQi m
2GQjHQi Q  X f hHQjQ,iqq,iQjHQi + O1=mQ : + c6;i m2 (10.112) Q i Equation (10.112) represents a master equation for a host of different inclusive heavy-flavor decays: semileptonic, nonleptonic and radiative transitions, CKM-favored or -suppressed, etc They can all be calculated through an OPE; the only difference lies in the operator LW Since that operator has a simpler structure for semileptonic than for nonleptonic transitions one might expect a faster convergence for the former than the latter expansion Yet a priori there is little reason for a qualitative difference here ! ! There are two leading classes of nonleptonic beauty decays, namely ,b cud and ,b ccs One finds ,NL B 0 ,decay B ; b cud + ,decay B ; b ccs (10.113) ,NLB , ,NLB 0 +
,PI B , (10.114) ' where ' ! ! m5 G ,decay B ; b ! cud = 192F 3b jVcbVud j2 hB jbbjB i "  !  A0 I x; 0; 0 + h2GiB x d , I x; 0; 0 , A h2GiB I x; 0; 0 m2b dx m2b G2F m5b jV V j2 hB jbbjB i ,decay B ; b ! ccs = 3192 3 cb cs "  !  A0 I x; x; 0 + h2GiB x d , I x; x; 0 , A h2GiB I x; x; 0 cc m2b dx m2b R EPORT OF THE BABAR P HYSICS WORKSHOP (10.115) (10.116) 10.4 Inclusive Properties of B Meson Decays 683 m2c The phase space factors I and I are defined as where x = m 2 b I0x; 0; 0 = 1 , x2 1 , 8x + x2  , 12x2 logx (10.117) I2 x; 0; 0 = 1 , x3 +v I0 x; x; 0 = v1 , 14x , 2x2 , 12x3  + 24x21 , x2 log 11 , v +v ; I2x; x; 0 = v1 + x2 + 3x2  , 3x1 , 2x2 log 11 , (10.118) v p with v = , 4x The quantities A0 , A2 and cc denote the QCD radiative corrections: A2 = c2+ , c2, = 4C1C2 ; A0 = c2, + 2c2+ J = 3C12 + 3C22 + 2C1C2 J (10.119) with J denoting the subleading logarithms The nonperturbative corrections through order 1=m2b enter through two quantities: The chromomagnetic moment h2GiB  hB jb 2i
GbjB i (10.120) which can be determined reliably from the hyperfine splitting h2GiB ' 34 MB2 , MB2  ' 0:37 GeV2  The expectation value (10.121) h p2b i h2GiB hB jbbjB i ' , + (10.122) 2m2b m2b where hp2b i is the average kinetic energy of the b quark inside the B meson and is estimated to be 0.4–0.5 GeV2 A lifetime difference arises in order 1=m3b
,PI B ,  = GF mb jVcbVudj2 fB2 ,4  8 MB "  + c2 c + , 2 = = 2 c+ , c, + ,  , 1c+ , c, (10.123) with  reflecting hybrid renormalization  " 1=b S 2had  S m2b  ; b = 11 , 32 nF ; R EPORT OF THE (10.124) BABAR P HYSICS WORKSHOP 684 Hadronic B Meson Decays leading to the prediction that the lifetime of charged B mesons exceeds that for neutral ones by several percent One should note here the absence of nonperturbative corrections of order 1=mb Strictly speaking the expansion parameter is the inverse of the energy release, rather than 1=mb ; therefore the result for ,B = bq cudq has to be viewed as intrinsically suspect since in it the energy release is not much larger than ordinary hadronic scales Together with ,SL B , one can then predict the lifetime ratios among beauty hadrons, their semileptonic branching ratios, SL B , and the charm content in the final state, nc ! B The predictions of the lifetime ratios for Bd0 and Bu+ are in good agreement with present data: B+  = 1:07 0:04, and there is no longer a clearcut discrepancy between predictions and data B0  for SL B  and nc It is possible that problems might (re)surface once more accurate data become available on B + = B  B  and nc The important point to note in any evaluation is that HQE predictions are deduced from QCD proper rather than from merely a model ansatz Thus, a failure of these predictions would be an important result This is exemplified by the discrepancy between the expected and the presently observed beauty baryon lifetime, where the expected value relative to the B lifetime b ' 0:90 , 0:95 B  HQE (10.125) is significantly larger than the world average measurements: b B  WA = 0:77  0:05 : (10.126) There is a lively debate on this issue in the theoretical literature, where four positions are advocated: (i) A violation of so-called local quark-hadron duality generating contributions of order has been established 1=mb (ii) Such a violation can actually be predicted which limits the numerical reliability of HQE results for nonleptonic, but not for semileptonic rates, since a weaker form of quark-hadron duality suffices for the latter (iii) There is no principal or qualitative distinction in the validity of quark-hadron duality in semileptonic and nonleptonic decays, but there are larger pre-asymptotic corrections for the widths of baryons than mesons that have not been brought under theoretical control yet due to the more complex structure of hadrons (iv) Wait for an upward movement of the measurements R EPORT OF THE BABAR P HYSICS WORKSHOP 10.4 Inclusive Properties of B Meson Decays 685 The foreseeable future will show whether position (iv) is vindicated If position (iii) is closest to the truth, then the predictions for the B meson lifetimes basically stay as quoted above Positions (i) and (ii) on the other hand would have serious consequences for B  as well making the present success of the HQE prediction a coincidence Further insights will be gained from more precise measurements of the lifetimes of charm-strange baryons and from ongoing theoretical work Without belittling the theoretical uncertainties, it seems fair to state that these total widths can now be described with decent accuracy within a theoretical rather than merely phenomenological framework More accurate data will yield further valuable lessons for hadronization in QCD 10.4.2 Semi-inclusive Transitions The two extreme regimes, of two-body modes on the one hand and total rates on the other, represent — for very different reasons — the areas where the most reliable theoretical tools for understanding nonleptonic transitions are available There is strong theoretical as well as experimental motivation to go beyond those regimes, i.e., to analyze semi-inclusive and genuine multibody channels Unfortunately theory can provide little quantitative guidance there: on the one hand the specifics of hadronization are essential in shaping the amplitudes, on the other the complexity of the final state is considerably higher than for the two-body modes The concept of factorization can be defined in several inequivalent ways, the most straightforward one is described in Section 10.1.5 One is forced to rely on phenomenological prescriptions However, some further help can be derived from theory beyond the provision of just the overall normalization of the fully integrated rates 10.4.3 Charm Production and Charm Counting The dominant B -decay modes proceed via the spectator tree diagram, and commonly involve the b c transition Only a small fraction ( Vub 2= Vcb 1) of decays proceed through b u Therefore, 0:99 charm quarks per B decay from b c are expected In addition, the virtual W in the loop can produce a cs or cd pair, which accounts for another 0:2 charm quarks, resulting in a total nc 1:2 A more precise number can be calculated on the quark level using the QCD operator-product expansion However, the results of these calculation vary with the values of unknown parameters such as the quark masses or the renormalization scale, and allow therefore a wide range of possible c-quark multiplicities Thereby the value of nc becomes related to other inclusive properties, such as the total semileptonic branching fraction and the ratio of B -mesons lifetimes ! j j j j  ! !   The multiplicity of charmed mesons is listed in Table 10-10 Although these numbers have reached a satisfactory experimental precision, they have fluctuated during the last few years One reason is the change in results on charmed-hadron branching fractions which still contribute significantly R EPORT OF THE BABAR P HYSICS WORKSHOP 686 Hadronic B Meson Decays Table 10-10 Charmed-meson multiplicities: experimental product branching fractions and values rescaled to current values of D branching fractions [8] The last error of the multiplicity is always due to the D branching fractions A best guess is indicated in bold typeface Particle D0 ! K ,  + D+ ! K ,  +  + D+ ! K , + + D+ ! K , + + 0 D+ ! D+ 0 +D0 + hni B 0:0194  :0015  :0025 0:0233  :0012  :0014 0:0251  :0006  :0007 0:0243  :0008 0:0209  :0027  :0040 0:0226  :0030  :0018 0:0216  :0008  :0008 0:0217  :0011 0:0071  :0006  :0012 0:00556  :00031  :00050 0:00655  :00034 a 0:00634  :00029 0:00639  :00054 hni 0:502  0:038  0:065  0:018 0:602  0:032  0:035  0:022 0:644  0:014  0:020  0:023 0:625  0:021  0:023 0:230  0:030  0:044  0:018 0:249  0:033  0:020  0:019 0:237  0:009  0:009  0:018 0:238  0:012  0:018 0:269  0:023  0:046  0:011 0:211  0:012  0:019  0:009 0:248  0:013  0:014  0:010 Experiment ARGUS 91 [81] CLEO 92 [82] CLEO 96 [83] average ARGUS 91 [81] CLEO 92 [82] CLEO 96 [83] average ARGUS 91 [81] CLEO 92 [82] CLEO 96 [83] :  0:019  0:014  0:026 0:239  0:011  0:014  0:009 0:234  0:013  0:009 D0 ! K , + 0 0:00620  :00031 0:259  0:013  0:019  0:015 Ds+ ! + 0:00306  :00047 0:085  0:013  0:021 0:00292  :00039  :00031 0:081  0:011  0:009  0:020 0:00424  :00014  :00030 0:118  0:004  0:009  0:029 0:00384  0:00028 0:100  0:007  0:025 + a For x 0:15 : 0:00570  0:00021, extrapolation from D  mode: +0:00085  0:00027 229 average CLEO 96 [83] CLEO 96 [83] average CLEO 96 [83] CLEO 90 [84] ARGUS 92 [85] CLEO 96 [86] average ! to the total error For example, the D0 K ,+ decay branching fraction has changed from 5:4 0:4 in 1986 to 3:86 0:14 in 1996 The most reliable value has been obtained by CLEO This one measurement dominates the present number; therefore, a second independent measurement of similar precision is highly desired The multiplicities in Table 10-10 have been rescaled to D0 K ,+ = 0:0386 0:0014, D+ K ,++ = 0:091 0:007, D+ D0+ = 0:683 0:014, D+ D+0 = 0:306 0:025, D0 D00 = 0:619 0:029, and Ds + = 0:036 0:009 [8]   B B ! !  B  !  B  ! B !  B  ! The results for the production of vector mesons are also included in Table 10-10 D -meson momentum spectra are shown in Fig 10-4, Ds spectra in Fig 10-5, and D spectra in Fig 10-6 All scales are renormalized to the world average multiplicities given in Table 10-10, except the D0 and Ds multiplicities where the most recent CLEO II results are used (as listed in Table 10-10, normalized to world average D branching fractions) The Ds spectrum has a pronounced soft R EPORT OF THE BABAR P HYSICS WORKSHOP 10.4 Inclusive Properties of B Meson Decays dn nB dp a 0:40 687 b 0:20 dn nB dp 0:15 0:10 0:20 0:05 0:0 0:5 1:0 1:5 2:0 2:5 p GeV=c 0:0 0:5 1:0 1:5 Figure 10-4 Inclusive momentum distribution of (a) D and D mesons (normalized to 0:644) and (b) D mesons in  4S decays [83] Only statistical errors are shown 2:0 2:5 p GeV=c hni = component in addition to a two-body-like peak This may be taken as an indication that not all Ds+ mesons are produced from W + cs, but some may contain the c quark from b c ! ! The relationship of D meson flavor to that of the parent B has been derived from D lepton charge correlations by CLEO [88] While these correlations had been used previously to measure the BB mixing probability, with the availability of a precise value for this from the time-dependent analyses at LEP, one can now use this flavor analysis to deduce the effectiveness of flavor tags If the ratio BB ! DX  = 0:100  0:026  0:016 BB ! DX  is the same for neutral and charged B mesons, it corresponds to a “wrong” sign fraction of 9:1 2:6 for all D mesons which would provide a “wrong” tag, or a dilution factor Dt = 0:82 0:05 The spectra of these D mesons are expected to differ, so that the momentum could serve as a discriminating variable to increase the tagging separation obtained with reconstructed D mesons Two caveats should be noted: first, the ratio for D mesons will differ, since the vector to pseudoscalar ratio is not the same for the dominant production mechanism in different flavorcorrelated channels Second, due to this fact the actual dilution for D and neutral D mesons can differ also   These correlations give for the first time information on the amount of D mesons from the b ! ccsd process (“upper vertex” charm production) The cd could produce D, or D, directly, while cs requires a quark-antiquark pair from the vacuum in addition, and can produce charged and neutral D mesons with equal probability A known process of the latter kind is the Ds ! DK R EPORT OF THE BABAR P HYSICS WORKSHOP 688 Hadronic B Meson Decays 0:15 dn nB dp 0:10 0:05 0:00 0:0 0:5 1:0 1:5 Figure 10-5 Inclusive momentum distribution of statistical errors are shown Ds 0:20 dn nB dp 0:15 0:20 a dn nB dp 0:15 0:10 0:10 0:05 0:05 0:0 0:5 1:0 1:5 2:0 2:5 p GeV=c 0:0 2:0 2:5 p GeV=c mesons in  4S decays [86] Only b 0:5 1:0 1:5 2:0 2:5 p GeV=c Figure 10-6 Inclusive momentum distribution of (a) D 0 and D 0 mesons and (b) D  mesons in  4S decays [83] Only statistical errors are shown R EPORT OF THE BABAR P HYSICS WORKSHOP 10.4 Inclusive Properties of B Meson Decays dn nB dp a 0:010 689 b 0:005 dn nB dp 0:005 0:000 0:0 0:5 1:0 1:5 2:0 2:5 p GeV=c 0:0 Figure 10-7 Inclusive momentum distribution of (a) decays [87] 0:5 J= 1:0 1:5 2:0 2:5 p GeV=c mesons and (b) c1 mesons in  4S decay, but nonresonant production is also possible More detailed studies at BABAR, including information on the lifetime difference to separate flavor changes from mixing, will shed more light on these mechanisms Complementing HQE with additional assumptions on how chiral symmetry and duality are implemented, the authors in Ref [89] infer the (somewhat surprising) result that at most half of the decays driven by b ccs contain a Ds in the final state They find ! ,B ! DK + X   ,B ! ccsq ; (10.127) which is supported by the data Charmonium states have been observed by ARGUS, Crystal Ball and CLEO All results are summarized in Table 10-11, rescaled to the best estimate of J= l+ l, Results for inclusive J= production have also been obtained at LEP [90, 91] However, since they correspond to a mixture including Bs mesons and beauty baryons, they can not be merged with results on the  4S The missing states can be estimated from theoretical predictions of the ratios [96] to be nc 0:006 and nhc 0:002, adding to a total of ncc-onium = 0:027 0:003 B h i h i ! h i  The total number of c and c quarks from B decays can be obtained by adding up all the charmed and charmonium states that decay into light flavors These are the charged and neutral D and Ds mesons listed in Table 10-10; the charmed baryons c and the c isodoublet listed in Table 10-15 (the c can be neglected due to its two s quarks); and charmonium states below the open charm threshold (from Table 10-11, subtracting the decay fractions into lower charmonium) which R EPORT OF THE BABAR P HYSICS WORKSHOP 690 Hadronic Table 10-11 Inclusive branching ratios to charmonium states rescaled to 6:02  0:19 B B Meson Decays BJ= ! l+l, = Experiment B ! J=X 1:34  0:24  0:04 1:23  0:27  0:04 1:28  0:44  0:04 1:11  0:05  0:04 1:12  0:05 B ! 0X incl 0:57  0:04J= 0:50  0:18  0:12 0:36  0:09  0:13 0:34  0:04  0:03 0:35  0:05 B ! c1X incl 0:273  0:016J= 1:20  0:40  0:23 0:39  0:06  0:04 0:41  0:07 B ! c2X incl 0:135  0:011J= 0:25  0:10  0:03 CLEO 86 [92] ARGUS 87 [93] Crystal Ball 90 [94] CLEO II 95 [87] average ARGUS 87 [93] CLEO [9] CLEO II 95 [87] average ARGUS 91 [95] CLEO II 95 [87] average CLEO II 95 [87] account for two c quarks The D branching fractions are still an important part of the uncertainty of this sum For example, Ds + = 3:6 0:9 is used, but previous measurements have resulted in numbers as low as 2 which would imply almost double the Ds multiplicity Similarly, smaller uncertainties apply to the other mesons Surprisingly, some product branching fractions given in Table 10-10 have also increased over time Therefore, the sum from the average of all measurements and the sum using only CLEO II data are listed side by side in Table 10-12 The weak tendency to a higher sum from more recent measurements may indicate a movement in the direction of the result predicted by theory B !  10.4.4 Production of Light Hadrons   The charged multiplicity in B decays is 5:45 0:03 0:12 which includes KS0 and  decay products [9, 97] CLEO finds about the same number of photons, n = 5:00 0:26 0:25 R EPORT OF THE BABAR P HYSICS WORKSHOP h i   10.4 Inclusive Properties of B Meson Decays 691 Table 10-12 Charm counting in B decays from average  4S data and from CLEO II data (Nc denotes charmed baryons) B ! D0 X B ! D+X B ! DsX B ! NcX  B !  : : :X sum Average CLEO II “Best guess” 0:625  0:031 0:238  0:022 0:100  0:026 0:070  0:005 0:054  0:006 1:09  0:05 0:644  0:034 0:237  0:022 0:118  0:031 0:059  0:022 0:052  0:006 1:11  0:06 0:644  0:034 0:238  0:022 0:118  0:031 0:070  0:005 0:054  0:006 1:12  0:05 The production of light flavor (u; d; s) hadrons in B decays is at the very end of the decay chain, and can therefore not be predicted from theory A simple model to describe inclusive B decays starts with two or four quarks according to QCD predictions, and uses a fragmentation model to produce the final state composition Monte Carlo event generators are based on this ansatz, and inclusive data are important input to tune these programs The light hadrons test the combined effect of B decays and subsequent charmed hadron decays This means that the branching fractions and decay models used for D and Ds mesons, and also for c and c baryons, have a significant influence on the light meson and baryon spectra A list of light-meson multiplicities is given in Table 10-13 Although these numbers sometimes appear in the literature as “branching fractions,” they are in fact average multiplicities, including multiple particles in the same event, as decay products from the same B meson These numbers are determined by measuring inclusive yields on the  4S, and subtracting the continuum contribution by using data taken at center-of-mass energies below the BB threshold These analyses give inclusive momentum distributions on the  4S, which are close to the distributions expected in the B rest system, since the boost of a B meson is only = 0:06 These spectra are therefore more useful for checking models of inclusive B decays used in Monte Carlo event generators, than are spectra obtained in bb jet events Figure 10-8 shows the spectrum of charged pions, which are the most abundant particles in B decays The measurement [98] is dominated by systematics rather than statistics, because it relies sensitively on the understanding of dE=dx and time-of-flight distributions used to separate pions from electrons, kaons, and protons The distributions of these parameters overlap substantially in the high-momentum region, and the particle types can only be separated by a fit of the data to these distributions The same procedure leads to the inclusive charged kaon spectrum shown in Fig 10-9a In addition, the faint crosses show a kaon spectrum obtained independently by reconstructing kaons that decay within the ARGUS drift chamber, and can be identified by the kink in their tracks This method suffers from poor statistics, but due to completely different systematics is a valuable consistency check Direct b s decays via penguin diagrams are expected to produce a hard kaon spec- ! R EPORT OF THE BABAR P HYSICS WORKSHOP 692 Hadronic B Meson Decays Table 10-13 Light-meson multiplicities in B decays These numbers are obtained as one-half of the mean number of produced particles per  4S decay A best guess is indicated in bold typeface hni Particle  Experiment 3:585  0:025  0:070 a 4:105  0:025  0:080 b ARGUS 92 [98] ARGUS 92 [98] 0:85  0:07  0:09 0:775  0:015  0:025 0:66  0:05  0:07 0:613  0:01  0:04 0:19  0:05  0:02 0:162  0:01  0:04 0:63  0:06  0:06 0:642  0:011  0:042 0:176  0:011  0:012 0:15 90CL 0:031  0:006  0:006 c 0:208  0:042  0:032 0:81 90CL 0:182  0:054  0:024 0:146  0:016  0:020 0:023  0:006  0:005 0:0390  0:0030  0:0035 K B ! K +X B ! K ,X K 0=K  0 ! K  K 0 =K 0 CLEO 87 [99] ARGUS 92 [98] CLEO 87 [99] ARGUS 92 [98, 100] CLEO 87 [99] ARGUS 92 [98, 100] CLEO 87 [99] ARGUS 92 [100] CLEO 96 [101] ARGUS 93 [102] CLEO 96 [103] ARGUS 94 [104] ARGUS 94 [104] ARGUS 94 [104] ARGUS 94 [104] CLEO 86 [105] ARGUS 94 [104] a without and decay products S b incl and decay products S c for 10 39 p K : K x   : trum Both K  and K (Fig 10-9b) momentum distributions are interesting in this respect The present data show no substantial excess, so no quantitative statement can be made within present knowledge of the details of spectator decays BABAR will be able to redo these measurements using the DIRC for particle identification This particle identification system will be able to separate pions from kaons with much less overlap, which leads to a significant reduction in systematic errors The performance can be verified with the help of reconstructed D0 K ,+, which may be separated from the background either by requiring a well-separated vertex, or by tagging with D+ D0+ production After a small period of data taking at the  4S and below the BB threshold, results with substantially improved errors can be obtained ! R EPORT OF THE BABAR P HYSICS WORKSHOP ! 10.4 Inclusive Properties of B Meson Decays 693 dn  c  nB dp GeV 0.0 1.0 2.0 p GeV=c 3.0 Figure 10-8 Inclusive momentum distribution of charged pions in  4S decays [98] Pions from K and  decays are subtracted Only statistical errors are shown The correlations between kaon charge (strangeness) and B flavor (beauty) have been investigated by CLEO [99] and ARGUS [100], by investigating kaon-lepton charge correlations Since this analysis has not yet been repeated with a tagged B sample, the rates given are for a mixture of charged and neutral B mesons, and their assignment to an individual type is based on simple Monte Carlo models The true experimental information is summarized in Table 10-14, and is a most unbiased test for an inclusive B decay model These data are the basis on which to estimate the performance of B flavor tagging via charged kaons Using the ARGUS data, and assuming an equal correlation for charged and neutral B mesons, one finds that charged kaons as B flavor tags have a dilution factor of Dt = 0:59 0:08 The spectra of flavor-neutral mesons such as  or  are not sensitive to the B flavor, but provide  useful information on the reliability of Monte Carlo models The  spectrum from CLEO is shown in Figure 10-10a Table 10-14 Kaon multiplicities in BB events with a lepton on the  4S BB ! l+; K +X BB ! l+; K ,X BB ! l+; KS0X CLEO [99] ARGUS [100] 0:54  0:07  0:07 0:10  0:05  0:02 0:195  0:03  0:02 0:594  0:021  0:056 0:086  0:011  0:044 0:226  0:019  0:028 R EPORT OF THE BABAR P HYSICS WORKSHOP 694 Hadronic a 1:0 dn nB dp 0:5 0:5 0:0 0:0 1:0 2:0 p GeV=c b 1:0 dn nB dp 0:0 B Meson Decays 3:0 0:0 1:0 2:0 p GeV=c 3:0 Figure 10-9 (a) Inclusive momentum distribution of charged kaons in  4S decays [98] The thin crosses are reconstructed from K  decays in the detector (b) Inclusive momentum distribution of neutral kaons in  4S decays [100] Only statistical errors are shown The production rates of some light flavor resonances is also shown in Table 10-13 The spectra of charged and neutral K  mesons are shown in Fig 10-10b These data can be substantially improved with BABAR data 10.5 B Meson Decays to Baryons B mesons are heavy enough to decay into baryons These decays could proceed via two-body decays to a baryon-antibaryon pair, with subsequent decays of baryon resonances to ground states, or via multibody decays A parton model ansatz has been invoked some time ago [106] to suggest in a semi-quantitative way that a substantial fraction of B meson decays lead to a baryon-antibaryon pair in the final state This has been borne out by the data When the B -meson decays into baryons, at least one additional quark pair has to be generated besides those created in the b-quark decay The three quarks and three antiquarks can then combine in many ways Hence decays into baryons are difficult to describe theoretically and there exists only a rudimentary literature Furthermore, with limited experimental b-flavor-tagging capability, there are often ambiguities in identifying baryons or antibaryons from a B decay, and this then requires taking into account even more production mechanisms In order to simplify the discussion, the decays of b (rather than b) quarks will always be considered in what follows R EPORT OF THE BABAR P HYSICS WORKSHOP 10.5 B Meson Decays to Baryons 0:25 dn nB dp 0:20 695 a 0:30 dn nB dp 0:20 b  K + K0 + K+ + K, 0:15 0:10 0:10 0:05 0:00 0:00 0:0 1:0 2:0 p GeV=c 3:0 0:0 1:0 2:0 p GeV=c 3:0 Figure 10-10 Inclusive momentum distribution (a) of  mesons [101], and (b) of K 0 and K  mesons in  4S decays [104] Only statistical errors are shown One usually distinguishes several contributions which are illustrated in Fig 10-11 The basic mechanism is a tree-level four-fermion interaction for a b c transition This can be replaced by b u or by a penguin graph in an obvious way ! ! ! The first mechanism is disintegration of the excited cq state from the b c transition and the spectator quark into a baryon anti-baryon pair (+ mesons) with “external” W -emission, where the emitted W transforms into a lepton and neutrino as in graph (a) or to mesons This requires at least two quark-antiquark pairs produced from the vacuum The accompanying meson(s) from the hadronization of the W have little phase space, hence W , cus is suppressed This mechanism would produce semileptonic decays to baryons even with an advantage in the available phase space, but only small upper limits have been observed: B pXl+  0:16 (90%CL) [107] and B cXl+ = B c=cX  0:05 (90%CL) [108]  ! B ! B ! B ! A very similar process works for “internal exchange” graphs where the emitted W boson interacts with the spectator quark in the B meson shown as graph (d) Another process is the recombination of all four quarks in a spectator decay into a baryon-antibaryon pair (+ mesons), using one additional quark-antiquark pair from the vacuum These are the “internal emission” graphs (b) and (c) Process (b) is the most favorable process given the available phase space  Process (e) is the very unlikely decay of the virtual W into a baryon-antibaryon pair (+ mesons) This, too, requires at least two quark-antiquark pairs produced from the vacuum R EPORT OF THE 0 BABAR P HYSICS WORKSHOP 696 Hadronic B Meson Decays l b B, u  ' ... left blank The BABAR Collaboration LAPP Annecy, Annecy-le-Vieux, France D Boutigny, I De Bonis, Y Karyotakis, R Lafaye, V Tisserand INFN Sezione di Bari, Bari, Italy C Evangelista, A Palano Beijing... SLAC Theory Group and the production staff of the SLAC Technical Publications Department for their invaluable and indefatigable work during the editing and production of the book R EPORT OF THE BABAR. .. experimentalists from the BABAR Collaboration Each chapter represents the contribution of a working group and presents both a theoretical summary of the relevant topics and the results of related simulation