# Hypernuclei and in-medium chiral dynamics - Nuclear Theory

Abstract: A recently introduced relativistic nuclear energy density functional,constrained by features of low-energy QCD, is extended to describe thestructure of hypernuclei. The density-dependent mean field and the spin-orbitpotential of a $\Lambda$-hyperon in a nucleus, are consistently calculatedusing the SU3 extension of in-medium chiral perturbation theory. The leadinglong-range $\Lambda N$ interaction arises from kaon-exchange and$2\pi$-exchange with a $\Sigma$-hyperon in the intermediate state. Scalar andvector mean fields, originating from in-medium changes of the quarkcondensates, produce a sizeable {\em short-range} spin-orbit interaction. Themodel, when applied to oxygen as a test case, provides a natural explanationfor the smallness of the effective $\Lambda$ spin-orbit potential: an almostcomplete cancellation between the background contributions scalar and vectorand the long-range terms generated by two-pion exchange.

Author: P. Finelli Department of Physics, University of Bologna

Source: https://arxiv.org/