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

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 its threshold decaying into the pi Sigma channel. Thus, the structure of Lambda(1405) is closely related to the (K) over barN 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 molecular component and is described as a superposition of two independent states. The meson-baryon nature of Lambda(1405) leads to various hadronic molecular 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. (C) 2011 Elsevier B.V. All rights reserved.