The nature of the Lambda(1405) resonance in chiral dynamics

TL;DR

This paper investigates the Lambda(1405) resonance, revealing it as a meson-baryon molecular state with a complex structure, using a chiral symmetry respecting coupled-channel model to deepen understanding of hadronic interactions involving strangeness.

Contribution

It introduces a dynamical coupled-channel model respecting chiral symmetry, demonstrating Lambda(1405) as a superposition of two states dominated by meson-baryon components.

Findings

Lambda(1405) is mainly a meson-baryon molecular state.

The resonance is described as a superposition of two independent states.

The structure influences the formation of hadronic molecules in strange systems.

Abstract

The Lambda(1405) baryon resonance plays an outstanding role in various aspects in hadron and nuclear physics. It has been considered that the Lambda(1405) resonance is generated by the attractive interaction of the antikaon and the nucleon, as a quasi-bound state below the threshold decaying into the pi Sigma channel. Thus, the structure of Lambda(1405) is closely related to the Kbar N interaction which is the fundamental ingredient to study few-body systems with antikaon. In this paper, after reviewing the basic properties of the Lambda(1405) resonance, we introduce the dynamical coupled-channel model which respects chiral symmetry of QCD and the unitarity of the scattering amplitude. We show that the structure of the Lambda(1405) resonance is dominated by the meson-baryon molecule component and is described as a superposition of two independent states. The meson-baryon nature of Lambda(1405) leads to various hadronic molecule states in few-body systems with strangeness which are hadron composite systems driven by the hadronic interactions. We summarize the recent progress in the investigation of the Lambda(1405) structure and future perspective of the physics of the Lambda(1405) resonance.