Abstract
The phase structure of baryonic matter is investigated with focus on the role of fluctuations beyond the mean-field approximation. The prototype test case studied is the chiral nucleon-meson model, with added comments on the chiral quark-meson model. Applications to nuclear matter include the liquid-gas phase transition. Extensions to high baryon densities are performed for both nuclear and neutron matter. The role of vacuum fluctuations is systematically explored. It is pointed out that such fluctuations tend to stabilize the hadronic phase characterized by spontaneously broken chiral symmetry, shifting the chiral restoration transition to very high densities. This stabilization effect is shown to be further enhanced by additional dynamical fluctuations treated with functional renormalisation group methods.
Highlights
The QCD phase diagram in the region of high baryon densities and low temperatures is still one of the great unknowns in the physics of the strong interaction
Extensions of the phase diagram to high densities at low temperatures from first-principles theory are hindered by the notorious sign problem of lattice QCD [4,5]
This section briefly introduces some basics of the field theoretical model and the schemes to be examined: mean-field (MF) approximation, and fluctuations beyond MF as they emerge from a functional renormalisation group (FRG) treatment
Summary
The QCD phase diagram in the region of high baryon densities and low temperatures is still one of the great unknowns in the physics of the strong interaction. Broken chiral symmetry at low energies implies that a chiral effective field theory of pions as Nambu-Goldstone bosons, coupled to nucleons as “heavy” fermions, is a valid framework for treating the nuclear many-body problem and its thermodynamics at sufficiently low densities and temperatures [20,21,22,23,24,25] Such perturbative approaches give reliable descriptions of both nuclear and neutron matter up to about twice the density of normal nuclear matter, n 2 n0. Resummed QCD perturbation theory [49] permits lowering the baryon density from extreme limits and favors a smooth matching to the EoS at typical neutron star central densities In all these and related considerations, a possible firstorder chiral phase transition, and the quest for a corresponding critical end point in the QCD phase diagram, have always been themes of prime interest [50,51,52,53].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
