B modes in the University

es the tensor-to-scalar ratio: BICEP2 then implies a lower bound on the sound speed: r 0.01 cs = > 16 Creminelli et al D’Amico and Kleban Naively, the bound weakens for large But, for new effects kick in: scale-invariance of the scalars is in danger tensors and scalars freeze at different times scalars tensors scalars tensors This leads to an extra suppression in the tensor-to-scalar ratio: r = 16 cs Ht Hs Summing Large Logs At next-to-leading order in slow-roll, one finds: This is large in the regime of interest Summing Large Logs At next-to-leading order in slow-roll, one finds: This is large in the regime of interest For we can solve the evolution exactly: DB, Green and Porto A New Bound on the Sound Speed 0.22 0.20 0.18 0.15 0.14 r 0.10 0.10 0.06 0.05 0.02 cs 0.05 0.1 "1 0.2 0.5 1.0 0.02 DB, Green and Porto A New Bound on the Sound Speed 0.25 0.14 0.21 0.12 cs 0.17 0.10 r 0.13 0.08 0.09 0.06 0.02 0.05 0.1 "1 0.2 0.5 1.0 0.05 DB, Green and Porto Summing Large Logs Extending to and , we find: tensors scalars DB, Green and Porto Expected Degeneracies Our bound would weaken if large But this has to be consistent with the scalar spectrum: is possible ns = s = 2 s Expected Degeneracies Our bound would weaken if large But this has to be consistent with the scalar spectrum: is possible ns = s = 2 Taking this into account strengthens the bound: I II strengthens the bound s ... Degeneracies Our bound would weaken if large But this has to be consistent with the scalar spectrum: is possible ns = s = 2 Taking this into account strengthens the bound: I II strengthens the bound s... Logs At next-to-leading order in slow-roll, one finds: This is large in the regime of interest For we can solve the evolution exactly: DB, Green and Porto A New Bound on the Sound Speed 0.22... extra suppression in the tensor-to-scalar ratio: r = 16 cs Ht Hs Summing Large Logs At next-to-leading order in slow-roll, one finds: This is large in the regime of interest Summing Large Logs