The phase and pole structure of the N*(1535) in piN-->piN and gammaN-->piN

TL;DR

This paper investigates the nature of the N*(1535) resonance by analyzing its role in piN and gammaN reactions, comparing models of it as a genuine resonance or a dynamically generated state, to understand its structure.

Contribution

The study provides a combined analysis of piN and gammaN reactions to test the meson-baryon components of N*(1535), offering insights into its dynamical generation versus genuine resonance nature.

Findings

The analysis favors a dynamically generated meson-baryon structure for N*(1535).

The results are consistent with predictions from the dynamical generation model.

The study highlights the importance of coupled-channel effects in understanding N*(1535).

Abstract

The nature of some baryonic resonances is still an unresolved issue. The case of the N*(1535) is particularly interesting in this respect due to the nearby etaN threshold and interference with the N*(1650). The N*(1535) has been described as a threshold effect, as a genuine 3-quark resonance, or as dynamically generated from the interaction of the octet of baryons with the octet of mesons. In the scheme of dynamical generation, predictions for the interaction of the N*(1535) with the photon can be made. In this study, we simultaneously analyze the role of the N*(1535) in the piN-->piN and gammaN-->piN reactions and compare to the respective amplitudes from partial wave analyses. This test is very sensitive to the meson-baryon components of the N*(1535).