Origin of resonances in the chiral unitary approach

TL;DR

This paper investigates the origins of resonances in the chiral unitary approach, proposing a natural renormalization scheme to distinguish between dynamically generated states and genuine quark states, with applications to meson-baryon scatterings.

Contribution

It introduces a natural renormalization method to differentiate between dynamically generated resonances and genuine quark states within the chiral unitary framework.

Findings

Lambda(1405) is mainly a meson-baryon molecule.

N(1535) has significant CDD pole contribution.

Meson-baryon dynamics influence both resonances.

Abstract

We study the origin of the resonances associated with pole singularities of the scattering amplitude in the chiral unitary approach. We propose a "natural renormalization" scheme using the low-energy interaction and the general principle of the scattering theory. We develop a method to distinguish dynamically generated resonances from genuine quark states [Castillejo-Dalitz-Dyson (CDD) poles] using the natural renormalization scheme and phenomenological fitting. Analyzing physical meson-baryon scatterings, we find that the Lambda(1405) resonance is largely dominated by the meson-baryon molecule component. In contrast, the N(1535) resonance requires a sizable CDD pole contribution, while the effect of the meson-baryon dynamics is also important.