The decays [formula omitted] and Bc → J/ψ + π(K) in covariant confined quark model

Aidos Issadykov,Mikhail A Ivanov

doi:10.1016/j.physletb.2018.06.056

Abstract

In the wake of the recent measurements of the decays Bc→J/ψπ(K) and Bc→J/ψℓνℓ reported by the LHCb Collaboration we calculate the form factors for the Bc→J/ψ and Bc→ηc 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 Bc meson. We find that the theoretical predictions on the ratios of RK+/π+ and Rπ+/μ+ν are in good agreement with last LHCb-data. However, the prediction for the RJ/ψ is found to be underestimated.

Highlights

The first measurement that relates semileptonic and hadronic decay rates of the Bc+ meson was performed by the LHCb Collaboration [1]
We evaluate the partial decay widths of the above-mentioned semileptonic and nonleptonic decays of the Bc meson and compare our predictions for the ratios Rπ+/μ+ν, RK+/π+, RJ/ψ with available experimental data given by Eqs. (1)-(3) and the results obtained in other approaches
At the same time the theoretical predictions for the ratio RJ/ψ are more than 2 σ less than the experimental data. This may indicate on the possibility of New physics effects in this decay

Summary

Introduction

The first measurement that relates semileptonic and hadronic decay rates of the Bc+ meson was performed by the LHCb Collaboration [1]. LHCb collaboration reported about measurement of the ratio of semileptonic branching fractions RJ/ψ [15]: RJ/ψ. This result lies within 2 standard deviations above the predictions obtained in several theoretical models Refs. The form factors of the transitions of the Bc into charmonia ηc and J/ψ have been calculated in our recent papers [20, 21] in the framework of the covariant confined quark model. The leptonic decay constants are calculated fP (V ) in the framework of the CCQM

Numerical results

Findings

Summary and discussion