$\Lambda_c \to \Lambda^*(1520)$ form factors from lattice QCD and improved analysis of the $\Lambda_b \to \Lambda^*(1520)$ and $\Lambda_b \to \Lambda_c^*(2595,2625)$ form factors

TL;DR

This paper presents the first lattice-QCD calculations of form factors for charm-baryon semileptonic decays, improving analysis methods and extending previous work on bottom-baryon decays to cover the full kinematic range.

Contribution

First lattice-QCD calculation of $ ext{Lambda}_c o ext{Lambda}^*(1520)$ form factors and an improved analysis of $ ext{Lambda}_b$ decay form factors using symmetry relations.

Findings

Determined form factors across the full kinematic range.

Updated analysis ensures correct angular behavior near endpoint.

Utilized multiple heavy-baryon momenta for accurate results.

Abstract

We present the first lattice-QCD calculation of the form factors governing the charm-baryon semileptonic decays $\Lambda_c \to \Lambda^*(1520)\ell^+\nu_\ell$. As in our previous calculation of the $\Lambda_b \to \Lambda^*(1520)$ form factors, we work in the $\Lambda^*(1520)$ rest frame, but here we use four different heavy-baryon momenta instead of just two. Because of the lower mass of the $\Lambda_c$, the moderately-sized momenta used here are sufficient to determine the form factors in the full kinematic range of the semileptonic decay. We also update the analysis of our lattice results for the $\Lambda_b \to \Lambda^*(1520)$ and $\Lambda_b \to \Lambda_c^*(2595,2625)$ form factors by imposing exact relations among the different form factors at zero recoil that follow from rotational symmetry. Imposing these relations ensures the correct behavior of the angular observables near the endpoint.