Hyperon non-leptonic decays in relativistic Chiral Perturbation Theory with resonances

TL;DR

This paper presents the first relativistic calculation of non-leptonic hyperon decays in Chiral Perturbation Theory at NLO, emphasizing the importance of resonances and fitting decay amplitudes.

Contribution

It introduces a relativistic NLO framework for hyperon decays, incorporating resonance saturation to estimate low-energy constants and fitting decay data.

Findings

Relativistic loop corrections are explicitly computed.

Resonance saturation significantly influences decay amplitudes.

A good fit to decay data is achieved, highlighting the role of resonances.

Abstract

Motivated by recent experimental advances in the corresponding measurements, non-leptonic hyperon decays are calculated, for the first time in a relativistic manner, in Chiral Perturbation Theory at next-to-leading order (NLO). On the one hand, relativistic loop corrections are computed explicitly based on the ground-state octet and decuplet fields. On the other hand, the NLO weak-transition low-energy constants are estimated by resonance saturation, inspired by the non-relativistic tree-level computation of Ref. [1]. In particular, the $1/2^-$ and the (excited) $1/2^+$ resonance octets are utilized. The remaining unknown parameters are fitted to the decay amplitudes. A good combined fit to both $s$- and $p$-wave amplitudes is achieved with the caveat of not being very tightly constrained. The role of the resonances is found to be crucial. Consequences for further investigations and open questions are addressed.