Distribution Amplitudes of the Lambda_b Baryon in QCD

TL;DR

This paper develops a comprehensive framework for the distribution amplitudes of the Lambda_b baryon in QCD, including their evolution and modeling, which is crucial for understanding its exclusive decay processes.

Contribution

It introduces the complete set of three-quark distribution amplitudes for Lambda_b and calculates their scale dependence, including the effects of evolution and modeling based on QCD sum rules.

Findings

Evolution generates a high-energy radiative tail.

Models show significant changes due to evolution.

Distribution amplitudes are essential for decay calculations.

Abstract

The QCD description of exclusive decays of the $\Lambda_b$ baryon involves hadronic matrix elements of non-local light ray operators, the light-cone distribution amplitudes. We introduce the complete set of three--quark distribution amplitudes and calculate the renormalization scale dependence for the leading twist. At leading order in the strong coupling the evolution is driven by pairwise two--quark interactions: heavy--light involving Sudakov logarithms as in the B-meson case, and light--light as in light mesons. We solve the evolution equation and show that its main effect is to generate a radiative tail extending to high energies. Finally, we present simple models for the distribution amplitudes based on QCD sum rules, and study the effect of the evolution on these models.