scholarly journals Equation of State and Composition of Proto-Neutron Stars and Merger Remnants with Hyperons

Universe ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 382
Author(s):  
Armen Sedrakian ◽  
Arus Harutyunyan
Keyword(s):  
Equation Of State ◽  
Density Functional ◽  
Chemical Potential ◽  
Isospin Symmetry ◽  
Zero Temperature ◽  
Electron Neutrinos ◽  
Degeneracy Point ◽  
Star Binary ◽  
Covariant Density ◽  
The Given

Finite-temperature equation of state (EoS) and the composition of dense nuclear and hypernuclear matter under conditions characteristic of neutron star binary merger remnants and supernovas are discussed. We consider both neutrino free-streaming and trapped regimes which are separated by a temperature of a few MeV. The formalism is based on covariant density functional (CDF) theory for the full baryon octet with density-dependent couplings, suitably adjusted in the hypernuclear sector. The softening of the EoS with the introduction of the hyperons is quantified under various conditions of lepton fractions and temperatures. We find that Λ, Ξ−, and Ξ0 hyperons appear in the given order with a sharp density increase at zero temperature at the threshold being replaced by an extended increment over a wide density range at high temperatures. The Λ hyperon survives in the deep subnuclear regime. The triplet of Σs is suppressed in cold hypernuclear matter up to around seven times the nuclear saturation density, but appears in significant fractions at higher temperatures, T≥20 MeV, in both supernova and merger remnant matter. We point out that a special isospin degeneracy point exists where the baryon abundances within each of the three isospin multiplets are equal to each other as a result of (approximate) isospin symmetry. At that point, the charge chemical potential of the system vanishes. We find that under the merger remnant conditions, the fractions of electron and μ-on neutrinos are close and are about 1%, whereas in the supernova case, we only find a significant fraction (∼10%) of electron neutrinos, given that in this case, the μ-on lepton number is zero.

scholarly journals Two-flavor chiral perturbation theory at nonzero isospin: pion condensation at zero temperature

2019 ◽  
Vol 79 (10) ◽  
Author(s):  
Prabal Adhikari ◽  
Jens O. Andersen ◽  
Patrick Kneschke
Keyword(s):  
Perturbation Theory ◽  
Equation Of State ◽  
Condensed Phase ◽  
Chiral Perturbation Theory ◽  
Chemical Potential ◽  
Tree Level ◽  
Zero Temperature ◽  
Leading Order ◽  
Chiral Perturbation ◽  
Pion Condensation

Abstract In this paper, we calculate the equation of state of two-flavor finite isospin chiral perturbation theory at next-to-leading order in the pion-condensed phase at zero temperature. We show that the transition from the vacuum phase to a Bose-condensed phase is of second order. While the tree-level result has been known for some time, surprisingly quantum effects have not yet been incorporated into the equation of state.  We find that the corrections to the quantities we compute, namely the isospin density, pressure, and equation of state, increase with increasing isospin chemical potential. We compare our results to recent lattice simulations of 2 + 1 flavor QCD with physical quark masses. The agreement with the lattice results is generally good and improves somewhat as we go from leading order to next-to-leading order in $$\chi $$χPT.

Calculation of equation of state of QCD at zero temperature and finite chemical potential

2010 ◽  
Vol 34 (9) ◽  
pp. 1324-1327
Author(s):  
Jiang Yu ◽  
Li Ning ◽  
Sun Wei-Min ◽  
Zong Hong-Shi
Keyword(s):  
Equation Of State ◽  
Chemical Potential ◽  
Zero Temperature

scholarly journals Proto-neutron stars with heavy baryons and universal relations

2020 ◽  
Vol 499 (1) ◽  
pp. 914-931
Author(s):  
Adriana R Raduta ◽  
Micaela Oertel ◽  
Armen Sedrakian
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Compact Stars ◽  
Zero Temperature ◽  
Functional Theory ◽  
Global Properties ◽  
Covariant Density Functional Theory ◽  
Heavy Baryons ◽  
The Moment ◽  
Covariant Density

ABSTRACT We use covariant density functional theory to obtain the equation of state (EoS) of matter in compact stars at non-zero temperature, including the full baryon octet as well as the Δ(1232) resonance states. Global properties of hot Δ-admixed hypernuclear stars are computed for fixed values of entropy per baryon (S/A) and lepton fraction (YL). Universal relations between the moment of inertia, quadrupole moment, tidal deformability, and compactness of compact stars are established for fixed values of S/A and YL that are analogous to those known for cold catalyzed compact stars. We also verify that the I–Love–Q relations hold at finite temperature for constant values of S/A and YL.

scholarly journals 2+1 flavors QCD equation of state at zero temperature within Dyson–Schwinger equations

2015 ◽  
Vol 30 (36) ◽  
pp. 1550217 ◽  
Author(s):  
Shu-Sheng Xu ◽  
Yan Yan ◽  
Zhu-Fang Cui ◽  
Hong-Shi Zong
Keyword(s):  
Phase Transitions ◽  
Equation Of State ◽  
Energy Density ◽  
Chemical Potential ◽  
Compact Stars ◽  
Zero Temperature ◽  
Number Density ◽  
Charge Neutrality ◽  
Quark Number ◽  
Research Fields

Within the framework of Dyson–Schwinger equations (DSEs), we discuss the equation of state (EOS) and quark number densities of 2+1 flavors, that is to say, [Formula: see text], [Formula: see text], and [Formula: see text] quarks. The chemical equilibrium and electric charge neutrality conditions are used to constrain the chemical potential of different quarks. The EOS in the cases of 2 flavors and 2+1 flavors are discussed, and the quark number densities, the pressure, and energy density per baryon are also studied. The results show that there is a critical chemical potential for each flavor of quark, at which the quark number density turns to nonzero from 0; and furthermore, the system with 2+1 flavors of quarks is more stable than that with 2 flavors in the system. These discussions may provide some useful information to some research fields, such as the studies related to the QCD phase transitions or compact stars.

A Model Study of Equation of State of QCD at Finite Chemical Potential and Zero Temperature

2009 ◽  
Vol 51 (3) ◽  
pp. 499-505
Author(s):  
Hou Feng-Yao ◽  
Jiang Yu ◽  
Sun Wei-Min ◽  
Zong Hong-Shi
Keyword(s):  
Equation Of State ◽  
Chemical Potential ◽  
Zero Temperature ◽  
Model Study

Statistical mechanics of cold deconfined quark matter using quasiparticle model

2020 ◽  
Vol 35 (13) ◽  
pp. 2050064
Author(s):  
P. Simji
Keyword(s):  
Equation Of State ◽  
Statistical Mechanics ◽  
Quark Matter ◽  
Chemical Potential ◽  
Zero Temperature ◽  
Quark Star ◽  
Consistency Relation ◽  
Quasiparticle Model ◽  
Thermodynamical Consistency

We discuss the statistical mechanics and thermodynamics of quark matter at zero temperature and finite chemical potential using a thermodynamically consistent framework of quasiparticle model for QGP without the need of any reformulation of statistical mechanics or thermodynamical consistency relation. Using that equation of state, we solve the Tolman–Oppenheimer–Volkoff equation to obtain the mass-radius relation of dense quark star.

scholarly journals Equation of State of Strongly Magnetized Matter with Hyperons and Δ-Resonances

Particles ◽  
2020 ◽  
Vol 3 (4) ◽  
pp. 660-675 ◽  
Author(s):  
Vivek Baruah Thapa ◽  
Monika Sinha ◽  
Jia Jie Li ◽  
Armen Sedrakian
Keyword(s):  
Magnetic Field ◽  
Equation Of State ◽  
Density Functional ◽  
Oscillatory Behavior ◽  
Functional Theory ◽  
Intense Magnetic Field ◽  
New Equation ◽  
Covariant Density ◽  
The Magnetic Field ◽  
Magnetic Case

We construct a new equation of state for the baryonic matter under an intense magnetic field within the framework of covariant density functional theory. The composition of matter includes hyperons as well as Δ-resonances. The extension of the nucleonic functional to the hypernuclear sector is constrained by the experimental data on Λ and Ξ-hypernuclei. We find that the equation of state stiffens with the inclusion of the magnetic field, which increases the maximum mass of neutron star compared to the non-magnetic case. In addition, the strangeness fraction in the matter is enhanced. Several observables, like the Dirac effective mass, particle abundances, etc. show typical oscillatory behavior as a function of the magnetic field and/or density which is traced back to the occupation pattern of Landau levels.

A MODEL STUDY OF THE EQUATION OF STATE OF QCD

2008 ◽  
Vol 23 (22) ◽  
pp. 3591-3612 ◽  
Author(s):  
HONG-SHI ZONG ◽  
WEI-MIN SUN
Keyword(s):  
Equation Of State ◽  
Chemical Potential ◽  
Direct Method ◽  
Quark Propagator ◽  
Ladder Approximation ◽  
Zero Temperature ◽  
New Approach ◽  
Model Study ◽  
Independent Constant ◽  
A Direct Method

In this paper, we give a direct method for calculating the partition function, and hence the equation of state (EOS) of QCD at finite chemical potential and zero temperature. In the EOS derived in this paper, the pressure density is the sum of two terms: the first term [Formula: see text] (the pressure density at μ = 0) is a μ-independent constant; the second term, which is totally determined by G[μ](p) (the dressed quark propagator at finite μ), contains all the nontrivial μ-dependence. By applying a general result in the rainbow-ladder approximation of the Dyson–Schwinger approach obtained in our previous study, Phys. Rev. C71, 015205 (2005), G[μ](p) is calculated from the model quark propagator proposed in Phys. Rev. D20, 2947 (1979). From this the full analytic expression of the EOS of QCD at finite μ and zero T is obtained. A comparison between our EOS and the cold, perturbative EOS of QCD of Fraga, Pisarski and Schaffner-Bielich is made. It is expected that our EOS can provide a possible new approach for the study of neutron stars. In the final part of this paper, our method is generalized to the case of finite temperature and the EOS of QCD at finite μ and T is derived. A comparison is made between the EOS derived in this paper and the EOS obtained in previous literatures by directly generalizing the CJT effective action at μ = 0 and T = 0 to finite μ and finite T.

Structure, Stability and Water Adsorption on Ultra-Thin TiO2 Supported on TiN

2019 ◽  
Author(s):  
Jose Julio Gutierrez Moreno ◽  
Marco Fronzi ◽  
Pierre Lovera ◽  
alan O'Riordan ◽  
Mike J Ford ◽  
...  
Keyword(s):  
Density Functional ◽  
Water Adsorption ◽  
Chemical Potential ◽  
Energy Gap ◽  
Molecular Water ◽  
Structure Stability ◽  
Ambient Conditions ◽  
Rutile Structure ◽  
The Stability ◽  
The One

<p></p><p>Interfacial metal-oxide systems with ultrathin oxide layers are of high interest for their use in catalysis. In this study, we present a density functional theory (DFT) investigation of the structure of ultrathin rutile layers (one and two TiO<sub>2</sub> layers) supported on TiN and the stability of water on these interfacial structures. The rutile layers are stabilized on the TiN surface through the formation of interfacial Ti–O bonds. Charge transfer from the TiN substrate leads to the formation of reduced Ti<sup>3+</sup> cations in TiO<sub>2.</sub> The structure of the one-layer oxide slab is strongly distorted at the interface, while the thicker TiO<sub>2</sub> layer preserves the rutile structure. The energy cost for the formation of a single O vacancy in the one-layer oxide slab is only 0.5 eV with respect to the ideal interface. For the two-layer oxide slab, the introduction of several vacancies in an already non-stoichiometric system becomes progressively more favourable, which indicates the stability of the highly non-stoichiometric interfaces. Isolated water molecules dissociate when adsorbed at the TiO<sub>2</sub> layers. At higher coverages the preference is for molecular water adsorption. Our ab initio thermodynamics calculations show the fully water covered stoichiometric models as the most stable structure at typical ambient conditions. Interfacial models with multiple vacancies are most stable at low (reducing) oxygen chemical potential values. A water monolayer adsorbs dissociatively on the highly distorted 2-layer TiO<sub>1.75</sub>-TiN interface, where the Ti<sup>3+</sup> states lying above the top of the valence band contribute to a significant reduction of the energy gap compared to the stoichiometric TiO<sub>2</sub>-TiN model. Our results provide a guide for the design of novel interfacial systems containing ultrathin TiO<sub>2</sub> with potential application as photocatalytic water splitting devices.</p><p></p>

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