Equation of state for hot and dense matter: model with scaled hadron masses and couplings

Abstract

The proposed earlier relativistic mean-field model with hadron masses and coupling constants depending on the σ-meson field is generalized to finite temperatures. Within this approach we simulate the in-medium behavior of the hadron masses motivated by the Brown-Rho scaling. The high-lying baryon resonances and boson excitations as well as excitations of the σ, ω and ρ fields interacting via mean fields are incorporated into this scheme. Thermodynamic properties of hot and dense hadronic matter are elaborated with the constructed equation of state. Even at zero baryon density, effective masses of σ-ω-ρ-N excitations abruptly drop down for T > ∼ 170 MeV and reach zero at a critical temperature T = T cσ ∼ 210 MeV. Below T cσ (at T ∼ 190 MeV) the specific heat gets a peak like at crossover. We demonstrate that our EoS can be matched with that computed on the lattice for high temperatures provided the baryon resonance couplings with nucleon are partially suppressed. In this case the quark liquid would masquerade as the hadron one. The model is applied to the description of heavy ion collisions in a broad collision energy range. It might be especially helpful for studying phase diagram in the region near possible phase transitions.

Effective equation of state of hot and dense matter in nuclear collisions around FAIR energy

“…The entropy per baryon ratio becomes constant here already at t = 4 fm/c. It is worth mentioning that similar kinks were observed in several quite different models, such as (i) lattice QCD simulations for 2-flavor medium [14]; (ii) σ − ω − ρ model with scaled hadron masses [15]; (iii) chiral fluid dynamics model with Polyakov loop [16] also along the lines of constant entropy per baryon. Despite the similarities, the origin of the phenomenon in microscopic calculations might not necessarily be the same.…”

Isospin-dependent properties of asymmetric nuclear matter in relativistic mean field models

“…In the nonlinear RMF model, we obtain from Eqs. (32) and (37) (119) which indicates that we always have M * Dirac,p > M * Dirac,n in the neutron-rich nuclear matter where ρ S,n > ρ S,p . This argument is also applicable to the densitydependent RMF model by replacing g δ with the density dependent Γ δ .…”

“…We note that there are some recent works [115,116,117,118,119] in which the standard RMF models are extended to include density-dependent hadron masses and meson coupling constants via the Brown-Rho (BR) scaling [120]. In particular, the parameter sets SLC and SLCd constructed in Ref.…”

On Manifestation of In-Medium Effects in Neutron Stars and Heavy-Ion Collisions

“…• and yield a mass-radius relation comparable with the empirical constraints including recent gravitation wave LIGO-Virgo detection [5]; • being extended to non-zero temperature T (for T < T c , where T c is the critical temperature of the deconfinement), appropriately describe supernova explosions, proto-neutron stars, and heavy-ion collision data [6,7], etc.…”

“…For more details, see discussion in [1,[6][7][8][9][10][11][12][13][14]. Most difficult is the ability to satisfy simultaneously the heavy-ion-collision flow and the maximum neutron-star mass constraints.…”