Angular distribution of the FCNC process $B_{c}\to{D}_{s}^{*}(\to{D}_{s}\pi)\ell^{+}\ell^{-}$

TL;DR

This paper investigates the angular distribution and related observables of the rare decay process $B_c o D_s^* o D_s \pi \ell^+\ell^-$ using a covariant light-front quark model to compute form factors, providing predictions for branching ratios and angular asymmetries.

Contribution

The study introduces a detailed analysis of the $B_c o D_s^*$ decay using the covariant light-front quark model, including predictions for angular observables and form factors, aiding future experimental tests.

Findings

Branching fractions for electron and muon channels can reach up to 10^{-8}.

Predicted angular observables can help distinguish new physics effects.

Results support ongoing LHCb measurements and deepen understanding of $b o s \ell^+\ell^-$ transitions.

Abstract

In this work, we study the flavor-changing neutral-current process $B_{c}\to{D}_{s}^{*}(\to{D}_{s}\pi)\ell^{+}\ell^{-}$ ($\ell$= $e$, $\mu$, $\tau$). The relevant weak transition form factors are obtained by using the covariant light-front quark model, in which, the main inputs, i.e., the meson wave functions of $B_{c}$ and $D_{s}^{*}$, are adopted as the numerical wave functions from the solution of the Schr\"{o}dinger equation with the modified Godfrey-Isgur model. With the obtained form factors, we further investigate the relevant branching fractions and their ratios, and some angular observables, i.e., the forward-backward asymmetry $A_{FB}$, the polarization fractions $F_{L(T)}$, and the $CP$-averaged angular coefficients $S_{i}$ and the $CP$ asymmetry coefficients $A_{i}$. We also present our results of the clean angular observables $P_{1,2,3}$ and $P^{\prime}_{4,5,6,8}$, which can reduce the uncertainties from the form factors. Our results show that the corresponding branching fractions of the electron or muon channels can reach up to $10^{-8}$. With more data being accumulated in the LHCb experiment, our results are helpful for exploring this process, and deepen our understanding of the physics around the $b\to{s}\ell^{+}\ell^{-}$ process.