Searching for New Physics in Semi-Leptonic Baryon Decays

Abstract

We propose two different and complementary observables for singling out possible signals of physics beyond the standard model in the semi-leptonic decays ${\Lambda }_b\to {\Lambda }_c\ell {\bar{\nu }}_{\ell }$, both with the $\tau$ lepton and with a light lepton. The two observables are the partial decay width and a T-odd asymmetry, whose respective sensitivities to scalar and/or pseudo-scalar coupling are calculated as functions of the parameters characterizing new physics. Two different form factors are used. Three particular cases are discussed and analyzed in detail.

Comments: 14 pages, 2 figures