Looking for the effects of New Physics in the ${\Lambda }_b⟶{\Lambda }_c(\to \Lambda \pi )\ell \nu$ decay mode

Abstract

One of the most pragmatic ways to look for the effects of New Physics at low energy scales is to study a detailed angular distribution of various decay modes, and in particular those based on $b\to c\ell {\bar{\nu }}_{\ell }$. In this paper we focus onto ${\Lambda }_b⟶{\Lambda }_c(\to \Lambda \pi )\ell \nu$ in a generic effective theory setup in which, besides the Standard Model, we allow for all the possible covariant dimension-six effective operators capturing the contributions arising at high energy scales, beyond the Standard Model. We list a number of observables that could be used as a diagnostic tool to check for the presence of New Physics and to discriminate among its various scenarios. We also briefly comment on ${\Lambda }_c\to \Lambda l\nu$.

33p, 6 figs [v2, 2 small typos corrected, 1 reference added]