Investigation on the New Physics effects of the vector leptoquark on semileptonic $$\bar{B}^
Jin-Huan Sheng (School of Physics and Electrical Engineering, Anyang Normal University, Anyang, Henan, 455000, China); Jie Zhu (School of Physics and Electrical Engineering, Anyang Normal University, Anyang, Henan, 455000, China); Quan-Yi Hu (School of Physics and Electrical Engineering, Anyang Normal University, Anyang, Henan, 455000, China)
In recent years, the experimental results about the ratio of the branching ratios $$R_{D^{(*)}}$$ and $$R_{K^{(*)}}$$ , which are in the semileptonic $$b\rightarrow c l \bar{\nu }_{l}$$ and $$b\rightarrow s l^+l^-$$ decays, have been observed to deviate from the Standard Model prediction by $$1.4\sigma $$ , $$2.5\sigma $$ , $$2.4\sigma $$ and $$2.2\sigma $$ respectively. Motivated by these anomalies and by the abundant $$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 $$ ). which is induced by $$b\rightarrow 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.