Electromagnetic mean squared radii of Lambda(1405) in chiral dynamics

TL;DR

This paper calculates the electromagnetic mean squared radii of Lambda(1405) using chiral dynamics, revealing its extended structure with K^- spread around the proton, and compares resonance and non-decay channel cases.

Contribution

It provides the first calculation of Lambda(1405)'s electromagnetic radii within a chiral unitary model, including complex values and decay channel effects.

Findings

Lambda(1405) has a negative, large electric mean squared radius.

The structure suggests K^- is widely spread around the proton.

Neglecting decay channels yields larger radii than typical baryons.

Abstract

The electromagnetic mean squared radii, <r^2>_E and <r^2>_M, of Lambda(1405) are calculated in the chiral unitary model. We describe the excited baryons as dynamically generated resonances in the octet meson and octet baryon scattering. We evaluate values of <r^2>_E and <r^2>_M for the Lambda(1405) on the resonance pole and obtain their complex values. We also consider Lambda(1405) obtained by neglecting decay channels. For the latter case, we obtain negative and larger absolute electric mean squared radius than that of typical ground state baryons. This implies that Lambda(1405) has structure that K^- is widely spread around p.