Octet-baryon axial-vector charges and SU(3)-breaking effects in the semileptonic hyperon decays

TL;DR

This paper uses covariant baryon chiral perturbation theory up to third order to analyze octet-baryon axial-vector charges and SU(3)-breaking effects in hyperon decays, revealing significant cancellations and the importance of analytic terms.

Contribution

It provides a comprehensive chiral analysis of axial-vector charges including explicit decuplet contributions and determines key low-energy constants D and F with controlled uncertainties.

Findings

Chiral expansion converges well with ~20% corrections at O(p^3).

Analytic terms are crucial alongside non-analytic ones for accurate description.

Determined low-energy constants D and F with quantified uncertainties.

Abstract

The octet-baryon axial-vector charges and the g1/f1 ratios measured in the semileptonic hyperon decays are studied up to O(p^3) using the covariant baryon chiral perturbation theory with explicit decuplet contributions. We clarify the role of different low-energy constants and find a good convergence for the chiral expansion of the axial-vector charges of the baryon octet, g1(0), with O(p^3) corrections typically around 20% of the leading ones. This is a consequence of strong cancellations between different next-to-leading order terms. We show that considering only non-analytic terms is not enough and that analytic terms appearing at the same chiral order play an important role in this description. The same effects still hold for the chiral extrapolation of the axial-vector charges and result in a rather mild quark-mass dependence. As a result, we report a determination of the leading order chiral couplings, D=0.623(61)(17) and F=0.441(47)(2), as obtained from a completely consistent chiral analysis up to O(p^3). Furthermore, we note that the appearance of an unknown low-energy constant precludes the extraction of the proton octet-charge from semileptonic decay data alone, which is relevant for an analysis of the composition of the proton spin.