Strange Nuclear Physics from QCD on Lattice

Abstract

We study single-particle potential of Lambda, Sigma, and Xi hyperons in nucleonic matter starting from the fundamental theory of the strong interaction, QCD. First we carry out a lattice QCD numerical simulation, and extract baryon-baryon interactions from QCD by means of the HAL QCD method. We employ a full QCD gauge configuration ensemble at almost physical point so that we can study the physical world, hence mass of hadrons are nearly physical, for example, pion mass is 146 MeV, kaon mass is 525 MeV, and nucleon mass is 958 MeV. Then, we apply the obtained hyperon interactions to the Brueckner-Hartree-Fock many-nucleon theory, and calculate single-particle potential of hyperons in nucleonic matter U_{Y}(k). We obtain for hyperons stopping in the symmetric nuclear matter at the normal nuclear matter density, U_{Lambda}(0)=-28 MeV, U_{Sigma}(0)=+15 MeV, and U_{Xi}(0)=-4 MeV with a statistical error about +/- 2 MeV associated with our Monte Carlo simulation. These results are qualitatively compatible with values suggested from hypernuclear experiments. This success is remarkable and very encouraging since this proves that our approach to strange nuclear physics starting from QCD is essentially correct.