Covariant calculation of strange decays of baryon resonances

TL;DR

This paper presents a covariant relativistic calculation of kaon decay widths of baryon resonances using constituent quark models, highlighting the importance of relativistic effects and comparing with nonrelativistic approaches.

Contribution

The study introduces a covariant, Poincare-invariant framework for calculating baryon resonance decay widths, emphasizing the significance of relativistic effects over nonrelativistic models.

Findings

Relativistic calculations generally underestimate experimental decay widths.

Decay widths with higher strangeness are extremely small in the models.

Nonrelativistic limit misses key Lorentz and spin effects.

Abstract

We present results for kaon decay widths of baryon resonances from a relativistic study with constituent quark models. The calculations are done in the point-form of Poincare-invariant quantum mechanics with a spectator-model decay operator. We obtain covariant predictions of the Goldstone-boson-exchange and a variant of the one-gluon-exchange constituent quark models for all kaon decay widths of established baryon resonances. They are generally characterized by underestimating the available experimental data. In particular, the widths of kaon decays with increasing strangeness in the baryon turn out to be extremely small. We also consider the nonrelativistic limit, leading to the familiar elementary emission model, and demonstrate the importance of relativistic effects. It is found that the nonrelativistic approach evidently misses sensible influences from Lorentz boosts and some essential spin-coupling terms.