HYP2018: 13th International Conference on Hypernuclear and Strange Particle Physics

Possibility of a new narrow Lambda* resonance near the Lambda eta threshold and a new experiment at J-PARC

Not scheduled

15m

2nd Floor

Abstract Submission

Speaker

Dr Kiyoshi Tanida (Japan Atomic Energy Agency)

Description

Evidence for a narrow ${\mathrm{\Lambda }}^{\ast }$ resonance at a mass of about 1665 MeV (just above the combined mass of the $\mathrm{\Lambda }$ ground state plus the $\eta$ meson) has been seen in the $M(p{K}^{-})$ mass of the Dalitz plot for ${\mathrm{\Lambda }}_c\to p{K}^{-}{\pi }^{+}$ decay at the Belle experiment [1]. Additional evidence for this resonance is found in the partial-wave analysis (PWA) of data on $K^{-}p$ reactions done independently by several groups [2-6], driven by angular distributions of the $K^{-}p\to \mathrm{\Lambda }\eta$ reaction by the Crystal Ball collaboration [7]. If a narrow ${\mathrm{\Lambda }}^{\ast }$ resonance exists at this mass, then the conventional quark model cannot explain it, and a possible explanation is that it is a crypto-exotic baryon with a dominant meson-baryon component to its wave function. Therefore we have proposed a definitive experiment for $K^{-}p\to \mathrm{\Lambda }\eta$, using the newly built hypTPC detector to establish the existence of the proposed narrow $\mathrm{\Lambda }(1665)$ and determine its spin and parity in just two weeks of beamtime at J-PARC (P72). We will discuss these evidences for the proposed ${\mathrm{\Lambda }}^{\ast }$ resonance and introduce the P72 experiment. [1] S. B. Yang {\em et al.} (Belle Collaboration), Phys. Rev. Lett. {\bf 117}, 011801 (2016). [2] H. Kamano, S.X. Nakamura, T.-S.H. Lee and T. Sato Phys. Rev. C {\bf 90}, 065204 (2014). [3] H. Kamano, S.X. Nakamura, T.-S.H. Lee and T. Sato Phys. Rev. C {\bf 92}, 025205 (2015); {\it ibid.}, {\bf 95}, 049903 (2017). [4] Bo-Chao Liu and Ju-Jun Xie, Phys. Rev. C {\bf 85}, 038201 (2012). [5] Bo-Chao Liu and Ju-Jun Xie, Phys. Rev. C {\bf 86}, 055202 (2012). [6] Jun Shi and Bing-Song Zou, Phys. Rev. C {\bf 91}, 035202 (2015). [7] A. Starostin {\em et al.,} (Crystal Ball collaboration), Phys. Rev. C {\bf 64}, 055205 (2001).