Exclusive weak B decays involving $\tau$ lepton in the relativistic quark model

TL;DR

This paper analyzes semileptonic and leptonic B decays involving tau leptons using a relativistic quark model, finding general consistency with experimental data but noting discrepancies in certain decay ratios.

Contribution

It provides new theoretical predictions for B decay branching fractions involving tau leptons within a relativistic quark framework, highlighting differences with recent experimental measurements.

Findings

Calculated decay branching fractions align with experimental data within errors.

Predicted ratios R(D) and R(D*) differ from measurements by 1.75σ and 2.4σ respectively.

The model offers insights into tau-involving B decays and their potential deviations from Standard Model expectations.

Abstract

Semileptonic and leptonic B decays are analyzed in the framework of the relativistic quark model. Special attention is payed to the decays involving $\tau$ lepton. It is found that the calculated particular decay branching fractions are consistent with available experimental data within error bars. However, the predicted and recently measured ratios $R(D^{(*)})$ of the $B\to D^{(*)}\tau\nu_\tau$ and $B\to D^{(*)}l\nu_l$ branching fractions differ by 1.75$\sigma$ for $R(D)$ and by 2.4$\sigma$ for $R(D^*)$.