Semileptonic $\Lambda_{b,c}$ to Nucleon Transitions in Full QCD at Light Cone

TL;DR

This paper calculates semileptonic Lambda_b and Lambda_c baryon transition form factors using light cone QCD sum rules, comparing results from QCD sum rules and lattice QCD, and analyzing their consistency with heavy quark symmetry.

Contribution

It provides a comprehensive calculation of transition form factors in full QCD for Lambda_b and Lambda_c baryons, incorporating different input parameters and comparing with existing models.

Findings

Results satisfy heavy quark symmetry for lattice inputs and Lambda_b case.

Maximum symmetry violation observed for Lambda_c with QCD sum rules.

Transition rates are computed and compared with other phenomenological approaches.

Abstract

The tree level semileptonic $\Lambda_{b}\to pl\nu$ and $\Lambda_{c}\to nl\nu$ transitions are investigated using the light cone QCD sum rules approach in full theory. The spin--1/2, $\Lambda_{Q}$ baryon with $Q=b$ or $c$, is considered by the most general form of its interpolating current. The time ordering product of the initial and transition currents is expanded in terms of the nucleon distribution amplitudes with different twists. Considering two sets of independent input parameters entering to the nucleon wave functions, namely, QCD sum rules and Lattice QCD parameters, the related form factors and their heavy quark effective theory limits are calculated and compared with the existing predictions of other approaches. It is shown that our results satisfy the heavy quark symmetry relations for lattice input parameters and b case exactly and the maximum violation is for charm case and QCD sum rules input parameters. The obtained form factors are used to compute the transition rates both in full theory and heavy quark effective theory. A comparison of the results on decay rate of $\Lambda_{b}\to pl\nu$ with those predicted by other phenomenological methods or the same method in heavy quark effective theory with different interpolating current and distribution amplitudes of the $\Lambda_{b}$ is also presented.