Studying W ' boson contributions in (B)over-bar - D-(*) l(-) (v)over-bar(l) decays within general SU(2)(1) circle times SU(2)(2) circle times U(1)(X) models

摘要

Recently, the Belle collaboration reported the first measurement of the tau lepton polarization P-tau (D*) in (B) over bar - D* tau(-)(v) over bar (tau) decay and a new measurement of the rate of the branching ratios R(D*), which are consistent with the Standard Model (SM) predictions. These could be used to constrain the New Physics (NP) beyond the SM. In this paper, we probe (B) over bar - D(*)l(-)(v) over bar (l) (l = e, mu, tau) decays in the model-independent way and in the specific G(221) models with lepton flavour universality. Considering the theoretical uncertainties and the experimental errors at the 95% C.L., we obtain the quite strong bounds on the model-independent parameters C'(LL), C'(LR), C'(RR), C'(RL), g(V), g(A), g'(V), g'(A) and the specific G(221) model parameter rates. We find that the constrained NP couplings have no obvious effects on all (differential) branching ratios and their rates, nevertheless, many NP couplings have very large effects on the lepton spin asymmetries of (B) over bar - D(*)l(-)(v) over bar (l) (l = e, mu, tau) decays and the forward-backward asymmetries of (B) over bar - D*l (v) over bar (l) . So we expect precision measurements of these observables would be researched by LHCb and Belle-II.