W-exchange contribution in hadronic decays of bottom baryon

TL;DR

This paper analyzes W-exchange contributions in nonleptonic decays of the bottom baryon \\Lambda_b, highlighting the dominant role of W exchange in certain decay modes and its impact on decay asymmetries.

Contribution

It provides a detailed analysis of W-exchange contributions to \\Lambda_b decays, including the effects on decay amplitudes and asymmetry parameters, with specific focus on factorization and baryon pole contributions.

Findings

W exchange dominates certain \\Lambda_b decay modes.

Factorization contributes only to parity-violating amplitude.

W exchange significantly influences decay asymmetry parameter \\alpha=-0.77.

Abstract

The nonleptonic decays of \Lambda_{b} that are dominated by W exchange are studied. In particular, the decay modes \varLambda_{b}\to\varDelta^{0}D^{0},\varDelta^{-}D^{+},\Sigma^{*-}D_{s}^{+}, \Lambda_{b}\to\Sigma_{c}^{*+}\pi^{-},\Sigma_{c}^{*0}\pi^{0},\Xi_{c}^{*0}K^{0} and \varLambda_{b}\to\Sigma_{c}^{+}\pi^{-} are analyzed. In an another aspect, the decay \Lambda_{b}\to\Lambda_{c}^{+}\pi^{-} in the factorization anstaz is studied. It is shown that factorization contributes to parity-violating (s-wave) amplitude A only. Hence factorization gives asymmetry parameter \alpha=0. However, the dominant contribution to parity conserving (p-wave) amplitude B comes from W exchange, i.e., from the baryon pole, giving asymmetry parameter \alpha=-0.77.