Searching for New Physics in Semi-Leptonic Baryon Decays

TL;DR

This paper introduces two observables in semi-leptonic Lambda_b decays to detect potential new physics signals beyond the standard model, focusing on scalar and pseudo-scalar couplings with different form factors.

Contribution

It proposes and analyzes two complementary observables, the partial decay width and T-odd asymmetry, for identifying new physics in Lambda_b decays involving tau and light leptons.

Findings

Sensitivity of observables to scalar and pseudo-scalar couplings calculated.

Two form factors used to evaluate the observables.

Three specific new physics scenarios analyzed in detail.

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.