Speaker
Description
The hyperon-nucleon interactions are fundamental information to describe many-body nucleon systems containing hyperons, such as hypernuclei and neutron stars. By extending the nuclear force to baryon-baryon interactions, we also can understand the nuclear force as the interaction between quark clusters, because new aspects of baryon-baryon interaction are expected to appear especially at short the distance in hyperon-nucleon and hyperon-hyperon interactions. Now, new attempts to describe the hyperon-nucleon interactions within the chiral effective field theory framework. In order to make such interaction theories more realistic, more hyperon-proton scattering data are necessary. In J-PARC, we succeeded in providing new and accurate Σ proton scattering data for three different channels. These new data are now used to constrain the theoretical models. From this April, we have just started Λp scattering experiment using photo-produced Λ particles at BL33LEP beam line in SPring-8 (HYPS experiment). We produce Λ particles via the γp→K+Λ reaction using γ beam of 1.5-2.4 GeV in a liquid hydrogen target. Then Λp scattering events will be detected by the same detector system (CATCH) used in the Σp scattering experiment. Now we plan to take data over 2.5 years to accumulate ~107 momentum-tagged Λ beam to detect several thousand Λp scattering events. In this experiment, differential cross sections of 0.3-0.6 GeV/c Λ momentum range will be derived. In J-PARC, we also proposed Λp scattering experiment (E86 experiment) to measure spin observables of Λp scattering using highly spin polarized Λ beam as a future program. In addition, a collaborative work between Lattice QCD calculation and ΣN cusp measurement is ongoing to reveal the full picture of the ΛN interaction. In this presentation, I will review the achievements of YN scattering experiments so far and introduce the ongoing and new projects to understand the ΛN interaction.
