摘要
During the past few years,signs of lepton flavor universality(LFU)violation have been observed in b→cτ■ and b→sl+l-transitions.Recently,the D* and τ polarization fractions P_L^D* and P_L~τ in B→D*τ■decay were likewise measured by the Belle collaboration.Motivated by these intriguing results,we revisit the RD(*)and RK(*) anomalies in a scalar leptoquark(LQ)model,where two scalar LQs,one of which is a S U(2)L singlet and the other a S U(2)L triplet,are introduced simultaneously.We consider five b→ cτ■ mediated decays,B→D(*)τ■,B^c→ηcτ■,Bc→J/ψt■,and ∧_b→∧_cτ■,and focus on the LQ effects on the q^2 distributions of the branching fractions,LFU ratios,and various angular observables in these decays.Under the combined constraints of the available data on RD(*),RJ/ψ,P_L~τ(D*),and pLD*,we perform scans for the LQ couplings and make predictions for a number of observables.Numerically it is found that both the differential branching fractions and LFU ratios are largely enhanced by the LQ effects,with the latter expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments.
During the past few years, signs of lepton flavor universality (LFU) violation have been observed in b→cτν and sl^+l^- transitions. Recently, the D^* and τ polarization fractions PL^D^* and PL^τ in B→D^*τν decay were likewise measured by the Belle collaboration. Motivated by these intriguing results, we revisit the RD^(*) and RK^(*) anomalies in a scalar leptoquark (LQ) model, where two scalar LQs, one of which is a singlet and the other a triplet, are introduced simultaneously. We consider five b→cτν mediated decays,B→D^(*)τν,Bc→ηcτν,Bc→J/ψτν, and ∧cτν, and focus on the LQ effects on the q^2 distributions of the branching fractions, LFU ratios, and various angular observables in these decays. Under the combined constraints of the available data on ,RD^(*),RJ/ψ, and PL^D^*, we perform scans for the LQ couplings and make predictions for a number of observables. Numerically it is found that both the differential branching fractions and LFU ratios are largely enhanced by the LQ effects, with the latter expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments.
作者
Han Yan
Ya-Dong Yang
Xing-Bo Yuan
颜涵;杨亚东;袁兴博(Institute of Particle Physics and Key Laboratory of Quark and Lepton Physics (MOE),Central China Normal University)
基金
Supported by the National Natural Science Foundation of China(11775092,11521064,11435003,11805077)
supported in part by the startup research funding from CCNU
