Lambda(1405) as a Resonance in the Baryon-Meson Scattering Coupled to the q^3 State in a Quark Model

TL;DR

This paper models Lambda(1405) as a resonance arising from baryon-meson scattering coupled with a three-quark state using a quark cluster model, explaining its observed peak below the N Kbar threshold.

Contribution

It introduces a coupled-channel quark model approach to describe Lambda(1405) as a resonance involving a q^3 state and baryon-meson scattering.

Findings

Peak appears below N Kbar threshold in the model.

Coupling to the q^3 pole is essential for the peak.

Using observed hadron masses is important for accurate results.

Abstract

In order to describe Lambda(1405) as a resonance in the baryon-meson scattering, we have investigated q^3-q qbar scattering system with the flavor-singlet q^3 (0s)^2(0p) state (the Lambda^1 pole). The scattering is treated by the quark cluster model (QCM). The Lambda^1 pole is treated as a bound state embedded in the continuum. We found that the peak appears below the N Kbar threshold in the spin one half, isospin 0 channel even if the mass of the Lambda^1 pole is above the threshold. This peak disappears when the coupling to the Lambda^1 pole is switched off. To use the observed hadron mass in the kinetic part of QCM is also found to be important to reproduce a peak just below the N Kbar threshold.