Eur. Phys. J. C (2021) 81: 524
https://doi.org/10.1140/epjc/s10052-021-09322-2

Regular Article - Theoretical Physics

Investigation on the New Physics effects of the vector leptoquark on semileptonic ${\overline{B}}^{\ast }\to V{\tau }^{-}\overline{{\nu }_{\tau }}$ decays

School of Physics and Electrical Engineering, Anyang Normal University, 455000, Anyang, Henan, China

^a jinhuanphy@aynu.edu.cn

Received: 8 May 2021
Accepted: 7 June 2021
Published online: 20 June 2021

Abstract

In recent years, the experimental results about the ratio of the branching ratios $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$, which are in the semileptonic $b\to cl{\overline{\nu }}_l$ and $b\to s{l}^{+}{l}^{-}$ 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 $B^{\ast }$ data samples, we investigate possible New Physics effects of the vector leptoquark in the semileptonic decay ${\overline{B}}_{u,d,s,c}^{\ast }\to V{\tau }^{-}{\overline{\nu }}_{\tau }$ ($V=D_{u,d,s}^{\ast },J/\psi$). which is induced by $b\to c{\tau }^{-}{\overline{\nu }}_{\tau }$ 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 $d{\Gamma }^{(L)}/d{q}^2({\overline{B}}_{u,d,s,c}^{\ast }\to V{\tau }^{-}{\overline{\nu }}_{\tau })$ and $R_V^{\ast (L)}(q^2)$ 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 $A_{\mathit{FB}}^{\tau }(q^2)$ , $P_{\tau }(q^2)$ and $F_L^{\ast V}(q^2)$. We hope that the numerical results in this work will be tested in the future high energy experiments.