Origin of resonances in chiral dynamics

TL;DR

This paper investigates the origins of baryon resonances using a chiral coupled-channel approach, distinguishing between dynamically generated states and genuine particles, and applying a natural renormalization scheme to analyze their structures.

Contribution

It introduces a method to separate genuine and dynamical resonance contributions via a natural renormalization scheme in chiral dynamics.

Findings

Lambda(1405) is predominantly dynamically generated.

Genuine contributions are significant for N(1535).

The approach clarifies the nature of baryon resonances.

Abstract

The nature of baryon resonances is studied in the dynamical chiral coupled-channel approach for meson-baryon scattering. In general, origin of resonances in two-body scattering can be classified into two categories: dynamically generated states and genuine elementary particles. We demonstrate that the genuine contribution in the loop function can be excluded by adopting a natural renormalization scheme. The origin of resonances can be studied by looking at the effective interaction in the natural renormalization scheme, which is deduced from the phenomenological amplitude fitted to experimental data. Applying this method to the baryon resonances, we find that the dominant component for the Lambda(1405) resonance is dynamical, while a genuine contribution plays a substantial role for the structure of the N(1535).