SU(3)-breaking corrections to the hyperon vector coupling $f_1(0)$ in covariant baryon chiral perturbation theory

TL;DR

This study calculates SU(3)-breaking corrections to hyperon vector couplings using covariant baryon chiral perturbation theory, including decuplet contributions, and finds positive corrections consistent with other theoretical approaches.

Contribution

First covariant ChPT analysis including decuplet contributions to hyperon vector couplings at $ ext{O}(p^4)$, providing predictions aligned with lattice QCD and large N_c results.

Findings

Positive SU(3)-breaking corrections to all $f_1(0)$s.

Decuplet contributions are significant and comparable to octet.

Results support more accurate extraction of $V_{us}$ from hyperon decays.

Abstract

We report on a recent study of the SU(3)-breaking corrections to the hyperon vector coupling $f_1(0)$ up to $\mathcal{O}(p^4)$ in covariant baryon chiral perturbation theory with dynamical octet and decuplet contributions. The decuplet contributions are taken into account for the first time in a covariant ChPT study and are found of similar or even larger size than the octet ones. We predict positive SU(3)-breaking corrections to all the four independent $f_1(0)$'s (assuming isospin symmetry), which are consistent, within uncertainties, with the latest results from large $N_c$ fits, chiral quark models, and quenched lattice QCD calculations. We also discuss briefly the implications of our results for the extraction of $V_{us}$ from hyperon decay data.