The decays $B_{c}\to J/\psi+\bar\ell\nu_\ell$ and $B_{c}\to J/\psi + \pi(K)$ in covariant confined quark model

TL;DR

This paper calculates form factors for specific Bc meson decays using a covariant confined quark model, compares predictions with recent LHCb data, and discusses areas of agreement and discrepancy.

Contribution

It provides new form factor calculations for Bc decays in the full kinematic range within a covariant confined quark model, aiding theoretical predictions.

Findings

Predicted ratios $ _{K^{+}/ \pi^{+}}$ and $ _{\pi^{+}/ \\mu^{+} u}$ agree with LHCb data.

Prediction for $ _{J/\\psi}$ is underestimated compared to experimental results.

Form factors calculated across the full kinematic region.

Abstract

In the wake of the recent measurements of the decays $B_c\to J/\psi\,\pi(K)$ and $B_c\to J/\psi\,\ell\nu_\ell$ reported by the LHCb Collaboration we calculate the form factors for the $B_c\to J/\psi$ and $B_c\to \eta_{c}$ transitions in full kinematical region within covariant confined quark model. Then we use the calculated form factors to evaluate the partial decay widths of the above-mentioned semileptonic and nonleptonic decays of the $B_{c}$ meson. We find that the theoretical predictions on the ratios of $\mathcal{R}_{K^{+}/ \pi^{+}}$ and $\mathcal{R_{\pi^{+}/ \mu^{+} \nu}}$ are in good agreement with last LHCb-data. However, the prediction for the $\mathcal{R}_{J/\psi}$ is found to be underestimated.