分类: 物理学 >> 核物理学 提交时间: 2016-09-14
摘要: Within the factorization-assisted topological-amplitude approach, we study the two-body charmed B meson decays Bu,d,s→D(∗)M, with M denoting a light pseudoscalar (or vector) meson. The meson decay constants and transition form factors are factorized out from the hadronic matrix element of topological diagrams. Therefore the effect of SU(3) symmetry breaking is retained, which is different from the conventional topological diagram approach. The number of free nonperturbative parameters to be fitted from experimental data is also much less. Only four universal nonperturbative parameters χC, ϕC, χE and ϕE are introduced to describe the contribution of the color suppressed tree and W-exchanged diagrams for all the decay channels. With the fitted parameters from 31 decay modes induced by b→c transition, we then predict the branching fractions of 120 decay modes induced by both b→c and b→u transitions. Our results are well consistent with the measured data or to be tested in the LHCb and Belle-II experiments in the future. Besides, the SU(3) symmetry breaking, isospin violation and CP asymmetry are also investigated.
分类: 物理学 >> 核物理学 提交时间: 2016-09-13
摘要: We calculate the tree and penguin amplitudes in the B0→π+π− decay channel employing the perturbative QCD factorization approach. Using the amplitudes as input with the theoretical uncertainties sufficiently considered, we constrain the UT angle γ to 53∘≤γ≤70∘, from the measurements of the CP violation parameters Cπ+π− and Sπ+π− in B0→π+π−. The U-spin breaking effect between B0→π+π− and B0s→K+K− is estimated to be around 30\%.