scholarly journals The physics of dense hadronic matter and compact stars

2007 ◽  
Vol 58 (1) ◽  
pp. 168-246 ◽  
Author(s):  
Armen Sedrakian
Keyword(s):  
Compact Stars ◽  
Hadronic Matter

scholarly journals Strange matter in compact stars

2018 ◽  
Vol 171 ◽  
pp. 08001 ◽  
Author(s):  
Thomas Klähn ◽  
David B. Blaschke
Keyword(s):  
Quark Matter ◽  
Strange Quark ◽  
Chiral Symmetry Breaking ◽  
Dense Matter ◽  
Strange Quark Matter ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Model Description ◽  
Severe Problem ◽  
Strange Matter

We discuss possible scenarios for the existence of strange matter in compact stars. The appearance of hyperons leads to a hyperon puzzle in ab-initio approaches based on effective baryon-baryon potentials but is not a severe problem in relativistic mean field models. In general, the puzzle can be resolved in a natural way if hadronic matter gets stiffened at supersaturation densities, an effect based on the quark Pauli quenching between hadrons. We explain the conflict between the necessity to implement dynamical chiral symmetry breaking into a model description and the conditions for the appearance of absolutely stable strange quark matter that require both, approximately masslessness of quarks and a mechanism of confinement. The role of strangeness in compact stars (hadronic or quark matter realizations) remains unsettled. It is not excluded that strangeness plays no role in compact stars at all. To answer the question whether the case of absolutely stable strange quark matter can be excluded on theoretical grounds requires an understanding of dense matter that we have not yet reached.

STRUCTURE OF COMPACT STARS WITH DENSE HADRONIC MATTER AT THE CORE

2012 ◽  
Vol 12 ◽  
pp. 350-357
Author(s):  
HYUN KYU LEE
Keyword(s):  
Symmetry Energy ◽  
Degrees Of Freedom ◽  
Chemical Potential ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Stellar Matter ◽  
Kaon Condensation ◽  
The Core ◽  
Weak Equilibrium

For a dense stellar matter, it is generally expected that as density increases, new degrees of freedom will emerge as the electron chemical potential becomes comparable to their energy scales. We discuss the nature of symmetry energy, which measures the energy relevant to the neutron-proton asymmetry and more importantly determines the electron chemical potential in weak equilibrium. The possible structure of compact stars with strangeness is briefly discussed for the case of kaon condensation.

Dark matter with chiral symmetry admixed hadronic matter in compact stars

2021 ◽  
Author(s):  
SiNa Wei ◽  
Zhaoqing Feng
Keyword(s):  
Dark Matter ◽  
Energy Density ◽  
Chiral Symmetry ◽  
Density Ratio ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Meson Exchange ◽  
Maximum Mass ◽  
Central Energy ◽  
Two Fluid

Abstract With the two-fluid TOV equation, the properties of dark matter (DM) admixed NSs (DANSs) have been studied. Different from previous studies, we found that increase of the maximum mass and decrease of the radius of 1.4 $M_\odot$ can occur simultaneously in DANS. This stems from the fact that the equation of state (EOS) of DM can be very soft at low density but very stiff at high density. It is well known that the IU-FSU and XS models can not reproduce the neutron star (NS) with a maximum mass greater than 2.0 $M_\odot$. However, considering IU-FSU and XS models in DANS, there are always mass and interactions of DM that can reproduce a maximum mass greater than 2.0 $M_\odot$ and the radius of 1.4 $M_\odot$ below 13.7km. The difference of DANS between the DM with chiral symmetry (DMC) and the DM with meson exchange (DMM) becomes obvious when the central energy density ratio of the DM is greater than one of the NM. When the central energy density ratio of the DM is greater than one of the NM, the DMC model with the DM mass of 1000 MeV still can reproduce a maximum mass greater than 2.0 $M_\odot$ and the radius of 1.4 $M_\odot$ below 13.7km. In the same case, although the maximum mass of DANS with the DMM model is greater than 2.0 $M_\odot$ , the radius of 1.4 $M_\odot$ with the DMM model will surpass 13.7km obviously. \com{In two-fluid system, it is worth noting that the maximum mass of DANS can be larger than 3.0 $M_\odot$. As a consequence, the dimensionless tidal deformability $\Lambda_{CP}$ of DANS with 1.4 $M_\odot$, which increase with increasing the maximum mass of DANS, could be larger than 800 when the radius of DANS with 1.4 $M_\odot$ is about 13.0km.}

EQUATION OF STATE FOR HYBRID COMPACT STARS WITH A NONLOCAL CHIRAL QUARK MODEL

2007 ◽  
Vol 16 (09) ◽  
pp. 2842-2846 ◽  
Author(s):  
A. G. GRUNFELD ◽  
J. BERDERMANN ◽  
D. B. BLASCHKE ◽  
T. KLÄHN ◽  
D. GÓMEZ DUMM ◽  
...  
Keyword(s):  
Quark Model ◽  
Compact Star ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Observational Constraints ◽  
Chiral Quark Model ◽  
Color Charge ◽  
Hybrid Star ◽  
Hartree Fock ◽  
Matter Phase

We study the thermodynamics of two flavor color superconducting (2SC) quark matter within a nonlocal chiral quark model, using both instantaneous and covariant nonlocal interactions. For applications to compact stars, we impose conditions of electric and color charge neutrality as well as β equilibrium and construct a phase transition to the hadronic matter phase described within the Dirac–Brueckner–Hartree–Fock (DBHF) approach. We obtain mass-radius relations for hybrid star configurations which fulfill modern observational constraints, including compact star masses above 2M⊙.

scholarly journals COLD DENSE BARYONIC MATTER AND COMPACT STARS

2011 ◽  
Vol 26 (25) ◽  
pp. 4311-4334 ◽  
Author(s):  
HYUN KYU LEE ◽  
MANNQUE RHO ◽  
SANG-JIN SIN
Keyword(s):  
Effective Field ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Baryonic Matter ◽  
Mass Generation ◽  
Quark Stars ◽  
Proton Mass ◽  
Starting Point ◽  
Basic Physics ◽  
To Come

Probing dense hadronic matter is thus far an uncharted field of physics. Here we give a brief summary of the highlights of what has been so far accomplished and what will be done in the years ahead by the World Class University III Project at Hanyang University in the endeavor to unravel and elucidate the multifacet of the cold dense baryonic matter existing in the interior of the densest visible stable object in the universe, i.e. neutron stars, strangeness stars and/or quark stars, from a modest and simplified starting point of an effective field theory modeled on the premise of QCD as well as from a gravity dual approach of hQCD. The core of the matter of our research is the possible origin of the ~ 99% of the proton mass that is to be accounted for and how the "vacuum" can be tweaked so that the source of the mass generation can be uncovered by measurements made in terrestrial as well as space laboratories. Some of the issues treated in the program concern what can be done — both theoretically and experimentally — in anticipation of what's to come for basic physics research in Korea.

scholarly journals NEUTRINO EMISSIVITY OF DENSE STARS

1996 ◽  
Vol 05 (02) ◽  
pp. 385-401 ◽  
Author(s):  
SANJAY K. GHOSH ◽  
S.C. PHATAK ◽  
P.K. SAHU
Keyword(s):  
Quark Matter ◽  
Strong Dependence ◽  
Nuclear Interaction ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Wide Range ◽  
Neutrino Emissivity ◽  
Relativistic Models ◽  
The Difference ◽  
Dense Stars

The neutrino emissivity of compact stars is investigated in this work. We consider stars consisting of nuclear as well as quark matter for this purpose. Different models are used to calculate the composition of nuclear and quark matter and the neutrino emissivity. Depending on the model under consideration, the neutrino emissivity of nuclear as well as quark matter varies over a wide range. We find that for nuclear matter, the direct URCA processes are allowed for most of the relativistic models without and with strange baryons, whereas for the nonrelativistic models this shows a strong dependence on the type of nuclear interaction employed. When the direct URCA processes are allowed, the neutrino emissivity of hadronic matter is larger than that of the quark matter by several orders of magnitude. We also find that the neutrino emissivity departs from T6 behavior when the temperature is larger than the difference in the Fermi momenta of the particles, participating in the neutrino-producing reactions.

scholarly journals TOWARDS AN EFFECTIVE FIELD THEORY FOR COLD COMPRESSED BARYONIC MATTER

2010 ◽  
Vol 25 (06) ◽  
pp. 399-422 ◽  
Author(s):  
WON-GI PAENG ◽  
MANNQUE RHO
Keyword(s):  
Field Theory ◽  
Effective Field Theory ◽  
Ion Beam ◽  
Local Symmetry ◽  
Effective Field ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Strong Interactions ◽  
Chiral Phase ◽  
Nuclear Matter Density

This is an extended version of the note taken by the first author (W.-G.P.) on a lecture given by the second author (M.R.) as a first part of the series on "Hadronic Matter Under Extreme Conditions," the principal theme of the WCU-Hanyang Program. It covers the attempts to go in a framework anchored on effective field theory of QCD from zero density to the nuclear matter density and slightly beyond, with the ultimate goal of arriving at the density relevant to compact stars, including chiral phase transition and quark matter. The focus is on the conceptual aspects rather than detailed "fitting" of the data on the kinds of physics that are being addressed to in radioactive-ion-beam machines in operation as well as in project (such as "KoRIA" in Korea) and will be explored at such forthcoming accelerators as FAIR/GSI. The approach presented here is basically different from the standard ones found in the literature in that the notion of hidden local symmetry — which underlies the chiral symmetry of the strong interactions — and its generalization to dual gravity description involving infinite tower of hidden gauge fields are closely relied on.

scholarly journals Structural properties of charged compact stars with color-flavor-locked quarks matter

2021 ◽  
Author(s):  
M. K. Jasim ◽  
Anirudh Pradhan ◽  
Ayan Banerjee ◽  
Takol Tangphati ◽  
Grigoris Panotopoulos
Keyword(s):  
Equation Of State ◽  
Structural Properties ◽  
Electric Charge ◽  
Mass Density ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Central Mass ◽  
Quark Stars ◽  
The Impact ◽  
Tov Equation

The observations of pulsars with masses close to [Formula: see text] have put strong constraints on the equation-of-state (EoS) of neutron-rich matter at supranuclear densities. Moreover, the exact internal composition of those objects is largely unknown to us. Aiming to reach the [Formula: see text] limit, here we investigate the impact of electric charge on properties of compact stars assuming that the charge distribution is proportional to the mass density. The study is carried out by solving the Tolman–Oppenheimer–Volkoff (TOV) equation for a well-motivated exotic quark matter in the color-flavor-locked (CFL) phase of color superconductivity. The existence of the CFL phase may be the true ground state of hadronic matter with the possibility of the existence of a pure stable quark star (QS). Concerning the equation-of-state, we obtain structural properties of quark stars and compute the mass, the radius as well as the total electric charge of the star. We analyze the dependence of the physical properties of these QSs depending on the free parameters with special attention on mass–radius relation. We also briefly discuss the mass versus central mass density [Formula: see text] relation for stability, the effect of electric charge and compactness. Finally, our results are compared with the recent observations data on mass–radius relationship.

scholarly journals Was GW170817 a Canonical Neutron Star Merger? Bayesian Analysis with a Third Family of Compact Stars

Universe ◽  
2020 ◽  
Vol 6 (6) ◽  
pp. 81 ◽  
Author(s):  
David Blaschke ◽  
Alexander Ayriyan ◽  
David Alvarez-Castillo ◽  
Hovik Grigorian
Keyword(s):  
Neutron Star ◽  
Bayesian Analysis ◽  
Quark Matter ◽  
Compact Star ◽  
Mass Range ◽  
Compact Stars ◽  
Hadronic Matter ◽  
Binary Mergers ◽  
Hybrid Stars ◽  
First Time

We investigate the possibility that GW170817 was not the merger of two conventional neutron stars (NS), but involved at least one if not two hybrid stars with a quark matter core that might even belong to a third family of compact stars. To this end, we develop a Bayesian analysis method for selecting the most probable equation of state (EoS) under a set of constraints from compact star physics, which now also include the tidal deformability from GW170817 and the first result for the mass and radius determination for PSR J0030+0451 by the NICER Collaboration. We apply this method for the first time to a two-parameter family of hybrid EoS based on the DD2 model with nucleonic excluded volume for hadronic matter and the color superconducting generalized nlNJL model for quark matter. The model has a variable onset density for deconfinement and can mimic the effects of pasta phases with the possibility of producing a third family of hybrid stars in the mass-radius diagram. The main findings of this study are that: (1) the presence of multiple configurations for a given mass (twins or even triples) corresponds to a set of disconnected lines in the Λ 1 – Λ 2 diagram of tidal deformabilities for binary mergers, so that merger events from the same mass range may result in a probability landscape with different peak positions; (2) the Bayesian analysis with the above observational constraints favors an early onset of the deconfinement transition, at masses of M onset ≤ 0.8 M ⊙ with an M–R relationship that in the range of observed neutron star masses is almost indistinguishable from that of a soft hadronic Akmal, Pandharipande, and Ravenhall (APR) EoS; (3) a few, yet fictitious measurements of the NICER experiment two times more accurate than the present value and a different mass and radius that would change the posterior likelihood so that hybrid EoS with a phase transition onset in the range M onset = 1.1–1.6 M ⊙ would be favored.

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