Applicability of perturbative QCD to $\Lambda_b \to \Lambda_c$ decays

TL;DR

This paper develops a perturbative QCD framework for analyzing the semileptonic decay of heavy baryons, providing a method to compute form factors and predict branching ratios with improved reliability.

Contribution

It introduces a perturbative QCD factorization theorem for $ ext{Lambda}_b o ext{Lambda}_c$ decays, including Sudakov resummation and predictions under heavy quark symmetry.

Findings

Perturbative QCD applies for velocity transfer > 1.2.

Predicted branching ratio is approximately 2%.

Determined $ ext{Lambda}_b$ and $ ext{Lambda}_c$ wave functions.

Abstract

We develop perturbative QCD factorization theorem for the semileptonic heavy baryon decay $\Lambda_b \to \Lambda_c l\bar{\nu}$, whose form factors are expressed as the convolutions of hard $b$ quark decay amplitudes with universal $\Lambda_b$ and $\Lambda_c$ baryon wave functions. Large logarithmic corrections are organized to all orders by the Sudakov resummation, which renders perturbative expansions more reliable. It is observed that perturbative QCD is applicable to $\Lambda_b \to \Lambda_c$ decays for velocity transfer greater than 1.2. Under requirement of heavy quark symmetry, we predict the branching ratio $B(\Lambda_b \to \Lambda_c l{\bar\nu})\sim 2%$, and determine the $\Lambda_b$ and $\Lambda_c$ baryon wave functions.