Current status of Lambda(1405) and its structure

by Prof. Tetsuo Hyodo (Yukawa Institute Tokio)

Monday 26 Oct 2015, 14:15 → 15:45 Europe/Berlin

3344 (TUM - Physics Department - Garching)

The understanding of the structure of the Λ(1405) resonance has been one of the central issues in hadron physics. In this talk, we discuss the current status and the internal structure of the Λ(1405). We first review the recent study of the Λ(1405) based on the coupled-channel approach for the meson-baryon scattering with next-to-leading order chiral interaction [1]. It is emphasized that the precise determination of the kaonic hydrogen and the comprehensive measurements of the pi Sigma mass spectrum in various production reactions are crucial to constrain the scattering amplitude. It is shown that the uncertainty in the pole structure is significantly reduced thanks to the theoretical and experimental developments. We then discuss the internal structure of the Λ(1405). We generalize the Weinberg’s compositeness relation to the case of unstable states using effective field theory [2]. Applying this result to the Lambda(1405), we show the dominance of the Kbar N molecule component in the Λ(1405), only from the model-independent relation and the experimentally observable quantities. [1] Y. Ikeda, T. Hyodo, W. Weise, Phys. Lett. B 706, 63-67 (2011); Nucl. Phys. A 881, 98-114 (2012). [2] Y. Kamiya, T. Hyodo, arXiv:1509.00146 [hep-ph]