Analysis of Semileptonic Decays of Some b-baryons Within the SM and Beyond

Abstract

The observation of flavor anomalies in semileptonic B meson decays $\overline{B}\rightarrow D(D^*){l}^- \overline{\nu }_{l}$ and $B_{c}\rightarrow J/\psi {l}^- \overline{\nu }_{l}$ motivates the study of similar decays mediated by $b\rightarrow c l{\nu _l}$ transitions at the quark level. In this work, we analyze some b-baryon decay modes $\Omega _b \rightarrow \Omega _c {\tau }^- \overline{\nu }_{\tau }$ and $\Xi _b \rightarrow \Xi _c {\tau }^- \overline{\nu }_{\tau }$, mediated by $b\rightarrow c \tau {\nu _\tau }$ transitions. We consider a general effective Hamiltonian which includes both standard model and new physics contributions, where new couplings are constrained using the experimental measurements of $R_{D^{(*)}}$,$R_{J/ \psi }$ and $BR(B_{c}^{+}\rightarrow \tau ^{+}\nu _{\tau })$. We study the effects of the new parameters on several observables such as the differential branching fraction, ratio of branching fractions, forward-backward asymmetry of the charged lepton and also longitudinal polarization of the charged lepton. Predictions for these observables within the standard model and in various new physics scenarios are presented here.