Probing new physics in semileptonic Λb decays

Abstract

In recent times, several hints of lepton nonuniversality have been observed in semileptonic B meson decays, both in the charged-current (b→clνl) and neutral-current (b→sll) transitions. Motivated by these intriguing results, we perform a model-independent analysis of the semileptonic Λb decays involving the quark level transitions b→(u,c)lνl, in order to scrutinize the nature of new physics. We constrain the new parameter space by using the measured branching ratios of the Bc,u+→τ+ντ, B→πτντ processes and the existing experimental results on the RD(∗), RJ/ψ, and Rπl parameters. Using the constrained parameters, we estimate the branching ratios, forward-backward asymmetries, and hadron and lepton polarization asymmetries of the Λb→(Λc,p)lνl processes. Moreover, we also examine whether there could be any lepton universality violation in these decay modes.