Y(nS)→B_c■■_■半轻衰变

Semileptonic Y(nS)→B_c■■_■ Decays

基于高亮度的重味物理实验产生大量Y介子.在标准模型中详细地研究了以树图贡献为主的Y(n S)→B_c■■_■(n=1,2,3)半轻衰变,给出了这些衰变过程的分支比,比值RY(nS),轻子自旋不对称和前后不对称.最终的数值结果表明,所有的Y(nS)→B_c■■_■的半轻衰变均有较大的分支比,且量级为10-10~10-9.因此,这些过程均有望被LHC和Supper KEKB/Belle-II实验所观测到.

Motivated by the abundant data samples Y at high-luminosity heavy-flavor experiments in the future, the tree- dominated and CKM-favored Y（nS）→Bceυe（n = 1, 2, 3） decays are studied within the Standard Model in this paper. The theoretical predictions for the observables including the branching fraction, the ratioRy（nS） ,the lepton spin asymmetry and the forward-backward asymmetry are presented. Numerically, the Y（nS）→Bceυe decays have relative large branching fractions ofthe order O（10^-10 - 10^-9） ,and are hopeful to be observed by the running LHC and upgrading SuperKEKB/Belle-II experi-ments in the future.