Analyzing lepton flavor universality in the decays $\Lambda_b\to\Lambda_c^{(\ast)}(\frac12^\pm,\frac32^-) + \ell\,\bar\nu_\ell$

TL;DR

This paper investigates lepton flavor universality in $ ext{Lambda}_b$ decays to various $ ext{Lambda}_c^{(*)}$ states, calculating decay rates and ratios for tau and muon modes using a covariant quark model to aid experimental tests.

Contribution

It provides theoretical predictions for decay rates and lepton flavor universality ratios in $ ext{Lambda}_b$ decays, utilizing a covariant confined quark model.

Findings

Calculated differential decay rates and branching fractions for $ ext{Lambda}_b$ decays.

Predicted rate ratios for tauonic and muonic modes as tests of lepton flavor universality.

Results serve as benchmarks for upcoming experimental analyses.

Abstract

Lepton flavor universality can be tested in the semileptonic decays $\Lambda_b\to \Lambda_c^{(\ast)}$ where $\Lambda_c^{(\ast)}$ denotes either the ground state $\Lambda_c(2286)$ (with $J^P=1/2^+$) or its orbital excitations $\Lambda_c(2595)$ (with $J^P=1/2^-$) and $\Lambda_c(2625)$ (with $J^P=3/2^-$). We calculate the differential decay rates as well as the branching fractions of these decays for both tauonic and muonic modes with form factors obtained from a covariant confined quark model previously developed by us. We present results for the rate ratios of the tauonic and muonic modes which provide important tests of lepton flavor universality in forthcoming experiments.