Analysis of Discrete Symmetries in b-Baryon Decays

TL;DR

This paper analyzes the decay channels of Lambda_b baryons into Lambda and vector mesons using helicity formalism and HQET, exploring symmetry violations and polarization effects to test fundamental symmetries.

Contribution

It combines kinematical and dynamical analyses with a model-independent approach to study symmetry violations in Lambda_b decays, including polarization and angular correlations.

Findings

Calculated branching ratios and helicity asymmetry parameters for specific decay channels.

Identified polarization components and correlations sensitive to time reversal violations.

Pointed out several CP- and CPT-odd observables for experimental tests.

Abstract

A study of the decay channels Lambda_{b}-->Lambda V, where V is a vector meson (1^-), has been done by putting together kinematical and dynamical analysis. An intensive use of the helicity formalism is involved on the kinematical side, while on the dynamical side, Heavy Quark Effective Theory (HQET) is applied to calculate the hadronic matrix elements between the baryons Lambda_{b} and Lambda. The branching ratios(BR) and helicity asymmetry parameters (alpha_{AS}) for Lambda_{b} --> Lambda J/psi, Lambda_{b} --> Lambda rho^0 and Lambda_{b} --> Lambda omega have been calculated. Since both the decay products are polarized, so they offer interesting opportunities to perform tests of time reversal, CP violation and of CPT invariance. A model independent parametrization is done via spin density matrix of the angular distribution, polarizations and some of polarization correlations of the decay products. The transverse component of the polarization and two polarization correlations are sensitive to time reversal violations. Moreover several CP- and CPT-odd observables are pointed out.