The nature of the Lambda(1405)

Abstract

We present here some results supporting the nature of the $Λ(1405)$ resonance as dynamically generated from the meson baryon interaction in coupled channels and resulting from the superposition of two close-by poles. We find support for this picture in the $K^- p \to π^0 π^0 Σ^0 $ reaction, which shows a different shape than the one obtained from the $π^- p \to K^0 πΣ$ reaction. We also call the attention to the $K^- p \to γπΣ$ with $πΣ$ in the $Λ(1405)$ region, which shows a narrow peak in the calculations around 1420 MeV. We also report on recent calculations of the radiative decay of the two $Λ(1405)$ states and on reactions to obtain information on these decay modes. Finally, we present results for the $pp\to p K^+Λ(1405)$ reaction recently measured at ANKE/COSY and compare them with theoretical results.

Talk given at the NSTAR2007 Workshop, Bonn September 2007