Remarks on nuclear matter: How an ω_{0} condensate can spike the speed of sound, and a model of Z (3 ) baryons
Abstract
I make two comments about nuclear matter. First, I consider the effects of a coupling between the O (4 ) chiral field, ϕ →, and the ω_{μ} meson, ∼+ϕ^{→2}ω_{μ}^{2}; for any net baryon density, a condensate for ω_{0} is unavoidably generated. I assume that with increasing density, a decrease of the chiral condensate and the effective ω_{0} mass gives a stiff equation of state (EOS). In order to match that onto a soft EOS for quarkyonic matter, I consider an O (N ) field at large N , where at nonzero temperature quantum fluctuations disorder, any putative pion "condensates" into a quantum pion liquid (Q π L ) [R. D. Pisarski et al., Phys. Rev. D 102, 016015 (2020), 10.1103/PhysRevD.102.016015]. In this paper, I show that the Q π L persists at zero temperature. If valid qualitatively at N =4 , the ω_{0} mass goes up sharply and suppresses the ω_{0} condensate. This could generate a spike in the speed of sound at high density, which is of relevance to neutron stars. Second, I propose a toy model of a Z (3 ) gauge theory with three flavors of fermions, where Z (3 ) vortices confine fermions into baryons. In 1 +1 dimensions, this model can be studied numerically with present techniques, using either classical or quantum computers.
 Publication:

Physical Review D
 Pub Date:
 April 2021
 DOI:
 10.1103/PhysRevD.103.L071504
 arXiv:
 arXiv:2101.05813
 Bibcode:
 2021PhRvD.103g1504P
 Keywords:

 Nuclear Theory;
 High Energy Physics  Lattice;
 High Energy Physics  Phenomenology
 EPrint:
 Slightly expanded from published version