Asymmetric nuclear matter in a parity doublet model with hidden local symmetry

Abstract

We construct a model to describe dense hadronic matter at zero and finite temperature, based on the parity doublet model of DeTar and Kunihiro, with including the iso-singlet scalar meson σ as well as ρ and ω mesons. We show that, by including a six-point interaction of σ meson, the model reasonably reproduces the properties of the normal nuclear matter with the chiral invariant nucleon mass m0 in the range from 500 MeV to 900 MeV. Furthermore, we study the phase diagram based on the model, which shows that the value of the chiral condensate drops at the liquid-gas phase transition point and at the chiral phase transition point. We also study asymmetric nuclear matter and find that the first order phase transition for the liquid-gas phase transition disappears in asymmetric matter and that the critical density for the chiral phase transition at non-zero density becomes smaller for larger asymmetry.

Impact of the Nuclear Equation of State on the Stability of Hybrid Neutron Stars

“…Selected properties of the hadronic equations of state (T = 0, µ C = 0) and their experimental constraints (cf. [34][35][36] As evident from Figure 1, the quark matter EoS differ depending on the choice of hadronic EoS. This difference is constant for a given temperature and charge chemical potential, as to be expected from Equations (31), (35) and (36).…”

Constraint to chiral invariant masses of nucleons from GW170817 in an extended parity doublet model

“…The properties of hot and/or dense matter including neutron star matter based on the parity doublet structure are widely studied in Refs. [11,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. In [11, 18-22, 24, 26, 28], the authors studied the relation between the chiral invariant mass and the incompressibility K of nuclear matter and their results show that the empirical value K ∼ 240 MeV only when the chiral invariant mass is close to nucleon's mass, m 0 ∼ 900 MeV.…”

“…In Ref. [29], six point interaction of scalar mesons was introduced and it was shown that the saturation properties are reproduced for wide region of the chiral invariant mass, i.e. 500 ≤ m 0 ≤ 900 MeV.…”

“…For the meson parts, we use the model introduced in Ref. [29]: the six point interaction of the scalar field is introduced and the ω and ρ mesons are included based on the hidden local symmetry [44,45]. We will show that requiring the saturation properties of normal nuclear matter excludes some combinations of two chiral invariant masses.…”

Mass Modifications of Light Mesons in Nuclear Matter with the Three Flavor Extended Linear Sigma Model

“…In this study, the nucleons are introduced by the twoflavor Parity Doublet Model (PDM) [38][39][40][41][42], and nuclear matter is constructed by the one-loop approximation of the nucleon together with the meson mean fields [43][44][45][46] obtained from the eLSM. In our approach, not only the vacuum properties of nucleons but also the nuclear matter properties such as the saturation density, the binding energy per a nucleon, and the incompressibility are successfully reproduced.…”