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Adopting hyperon-nucleon and hyperon-nucleon-nucleon interactions parametrized in chiral effective field theory, single-particle potentials of the $Lambda$ and $Sigma$ hyperons are evaluated in symmetric nuclear matter and in pure neutron matter within the framework of lowest order Bruckner theory. The chiral NLO interaction bears strong $Lambda$N-$Sigma$N coupling. Although the $Lambda$ potential is repulsive if the coupling is switched off, the $Lambda$N-$Sigma$N correlation brings about the attraction consistent with empirical data. The $Sigma$ potential is repulsive, which is also consistent with empirical information. The interesting result is that the $Lambda$ potential becomes shallower beyond normal density. This provides the possibility to solve the hyperon puzzle without introducing ad hoc assumptions. The effects of the $Lambda$NN-$Lambda$NN and $Lambda$NN-$Sigma$NN three-baryon forces are considered. These three-baryon forces are first reduced to normal-ordered effective two-baryon interactions in nuclear matter and then incorporated in the $G$-matrix equation. The repulsion from the $Lambda$NN-$Lambda$NN interaction is of the order of 5 MeV at the normal density, and becomes larger with increasing the density. The effects of the $Lambda$NN-$Sigma$NN coupling compensate the repulsion at normal density. The net effect of the three-baryon interactions to the $Lambda$ single-particle potential is repulsive at higher densities.
The $Xi$ single-particle potential obtained in nuclear matter with the next-to-leading order baryon-baryon interactions in chiral effective field theory is applied to finite nuclei by an improved local-density approximation method. As a premise, phas
The effective chiral theory of the in-medium NN interactions is considered. The shallow bound states, which complicate the effective field theory analysis in vacuum do not exist in matter. We show that the next-to-leading order terms in the chiral
We derive from the subleading contributions to the chiral three-nucleon interaction [published in Phys.~Rev.~C77, 064004 (2008) and Phys.~Rev.~C84, 054001 (2011)] their first-order contributions to the energy per particle of isospin-symmetric nuclear
We report on the recent studies of leading order baryon-baryon interactions in covariant baryon chiral perturbation theory. In the strangeness $S=0$ sector, one can achieve a rather good description of the Nijmegen $np$ phase shifts with angular mome
We present a study of the symmetry energy (a_s) and its slope parameter (L) of nuclear matter in the general framework of the Landau-Migdal theory. We derive an exact relation between a_s and L, which involves the nucleon effective mass and three-par