Comment on Implications of new physics in the decays $B_c \to (J/\psi,\eta_c)\tau\nu$

TL;DR

This paper discusses the implications of new physics in B_c meson decays to J/psi or eta_c with tau neutrinos, highlighting how existing lattice QCD results can improve matrix element estimates for BSM corrections.

Contribution

It points out that lattice QCD results can be used to determine matrix elements previously estimated with the covariant confining quark model, enhancing the analysis of BSM effects.

Findings

Lattice QCD provides reliable matrix elements for B_c decays.

Reassessment of BSM corrections using lattice data.

Potential impact on interpreting new physics signals.

Abstract

As part of a study BSM corrections to leptonic decays of the $B_c$ meson, Tran et al. (arXiv:1801.06927) use the covariant confining quark model (CCQM) to estimate the matrix element of the pseudo-scalar curent between the vacuum and the $B_c$ meson. We note that this matrix element can be determined using existing lattice QCD results.