Investigation on the New Physics effects of the vector leptoquark on semileptonic bar{B}^*rightarrow V tau ^-bar{nu _{tau }} decays

Abstract

In recent years, the experimental results about the ratio of the branching ratios R_{D^{(*)}} and R_{K^{(*)}}, which are in the semileptonic brightarrow c l bar{nu }_{l} and brightarrow s l^+l^- decays, have been observed to deviate from the Standard Model prediction by 1.4sigma , 2.5sigma , 2.4sigma and 2.2sigma respectively. Motivated by these anomalies and by the abundant B^* data samples, we investigate possible New Physics effects of the vector leptoquark in the semileptonic decay bar{B}^*_{u,d,s,c} rightarrow V tau ^-bar{nu }_{tau } (V=D^*_{u,d,s},J/psi ). which is induced by brightarrow c tau ^-bar{nu }_{tau } at the quark level. Using the best fit solutions for the new operator Wilson coefficients and the relevant form factors which are obtained in the light-front quark model, we find that (i) the contributions of the vector leptoquark to d{varGamma }^{(L)}/dq^2(bar{B}^*_{u,d,s,c} rightarrow V tau ^-bar{nu }_{tau }) and R^{*(L)}_{V}(q^2) to be significant; (ii) the two best fit solutions in the vector leptoquark are indistinguishable from each other and give similar amounts of enhancements to these two observables; (iii) both two cases of the vector leptoquark give nearly same results as those of the Standard Model for A_{FB}^{tau }(q^2) , P_{tau }(q^2) and F_{L}^{*V}(q^2). We hope that the numerical results in this work will be tested in the future high energy experiments.