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

TL;DR

This paper investigates the Lambda(1405) hyperon resonance using a chiral unitary model, revealing it as composed of two resonance states with different couplings, affecting its spectral observations and emphasizing its role as a Kbar N quasibound state.

Contribution

The study demonstrates that Lambda(1405) consists of two resonance states with distinct coupling properties, providing a detailed phenomenological description within the chiral dynamics framework.

Findings

Lambda(1405) is made of two resonance states with different meson-baryon couplings.

The resonance position depends on the initial production channel.

K^- d to Lambda(1405) n is a promising reaction to observe Lambda(1405).

Abstract

The nature of the Lambda(1405) is discussed based on the unitarised coupled-channels approach with chiral dynamics (chiral unitary model). This approach describes the Kbar N scattering cross sections and the Lambda(1405) spectra phenomenologically very well. With this successful description of Lambda(1405), it is found that the Lambda(1405) is composed by two resonance states having different coupling nature to the meson-baryon states. As a consequence, the resonance position in the pi Sigma invariant mass spectrum depends on the initial channel of the Lambda(1405) production. To observe the Lambda(1405) initiated by the Kbar N channel, K^- d to Lambda(1405) n is one of the most favorable reactions. Hadronic molecule states with kaons are also discussed by emphasizing an important role of Lambda(1405) as a quasibound state of Kbar N.