Might Normal Nuclear Matter be Quarkyonic?

Abstract

The possibility that nuclear matter might be Quarkyonic is considered. Quarkyonic matter is high baryon density matter that is confined but can be approximately thought of as a filled Fermi sea of quarks surrounded by a shell of nucleons. Here, nuclear matter is described by the IdylliQ sigma model for Quarkyonic matter, generalizing the non-interacting IdylliQ model [Y. Fujimoto et al., Phys. Rev. Lett. 132, 112701 (2024) [arXiv:2306.04304]] to include interactions with a sigma meson and a pion. When such interactions are included, we find that isospin-symmetric nuclear matter binds, with acceptable values of the compressibility and other parameters for nuclear matter at saturation. The energy per nucleon and sound velocity of such matter is computed, and the isospin dependence is determined. Nuclear matter is formed at a density close to but slightly above the density at which Quarkyonic matter forms. Quarkyonic matter predicts a strong depletion of nucleons in normal nuclear matter at low momentum. Such a depletion for nucleon momenta $k \lesssim 120$ MeV is shown to be consistent with electron scattering data.