Neutron Stars with Exotic Cores

Abstract

It has been recognized since the 1960s that with increasing density ρ above the standard nuclear-matter density ρ₀ the matter can undergo phase transitions to states qualitatively different from the state at ρ ∼ ρ₀. These high-density phases are exotic by the standards of terrestrial nuclear physics. Their possible existence above some threshold densities results from assumed specific features of strong (hadronic) interactions (pion condensation, kaon condensation) and the quark structure of baryons (quark deconfinement).