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We find some exact solutions for constant-density and quark matter equations of state in stellar structure models framed within the $f(R,T)=R+\lambda \kappa^2 T$ theory of gravity, where $R$ is the curvature scalar, $T$ the trace of the…

General Relativity and Quantum Cosmology · Physics 2025-04-09 Aliya Batool , Abdul Malik Sultan , Gonzalo J. Olmo , Diego Rubiera-Garcia

The properties of compact stars and in particular the existence of twin star solutions are investigated within an effective model that is constrained by lattice QCD thermodynamics. The model is modified at large baryon densities to…

Nuclear Theory · Physics 2021-01-20 P. Jakobus , A. Motornenko , R. O. Gomes , J. Steinheimer , H. Stoecker

Updated constraints from neutron star masses and radii impose stronger restrictions on the equation of state for baryonic matter at high densities and low temperatures. The existence of two-solar-mass neutron stars rules out many soft…

Nuclear Theory · Physics 2015-06-18 Thomas Hell , Wolfram Weise

We apply an extended version of the SU(3) parity model, containing quark degrees of freedom, to study neutron stars. The model successfully reproduces the main thermodynamic features of QCD which allows us to describe the composition of…

High Energy Astrophysical Phenomena · Physics 2015-06-05 V. Dexheimer , J. Steinheimer , R. Negreiros , S. Schramm

As a model for nonideal behavior in the equation of state of QCD at high density, we consider cold quark matter in perturbation theory. To second order in the strong coupling constant, $\alpha_s$, the results depend sensitively on the…

High Energy Physics - Phenomenology · Physics 2009-12-31 Eduardo S. Fraga , Robert D. Pisarski , Jurgen Schaffner-Bielich

We investigate the structure of quark stars in the framework of $f(R)= R+ \alpha R^2$ gravity using an equation of state for cold quark matter obtained from perturbative QCD, parametrized only by the renormalization scale. We show that a…

General Relativity and Quantum Cosmology · Physics 2022-07-12 José C. Jiménez , Juan M. Z. Pretel , Eduardo S. Fraga , Sergio E. Jorás , Ribamar R. R. Reis

We study the equation state of strongly interacting quark matter within a NJL-like model in which the chiral condensates and the color superconducting gaps are computed self-consistently as a function of the baryon density. A vector…

Astrophysics · Physics 2008-11-26 G. Pagliara , J. Schaffner-Bielich

The nonlinear chiral extension of colour dielectric model has been used in the present work to study the properties of quark stars. Assuming that the square of meson fields develop nonzero expectation value, the thermodynamic potential for…

Astrophysics · Physics 2015-06-24 Sanjay K. Ghosh , Pradip K. Sahu

We describe an extension of the hadronic SU(3) non-linear sigma model to include quarks. As a result, we obtain an effective model which interpolates between hadronic and quark degrees of freedom. The new parameters and the potential for…

Solar and Stellar Astrophysics · Physics 2010-04-20 V. A. Dexheimer , S. Schramm

In the framework of Einstein's the theory of general relativity we present a new interior solution with a perfect fluid, this is constructed from the proposal of a gravitational redshift factor. The geometry is regular and its density and…

General Relativity and Quantum Cosmology · Physics 2019-10-02 Gabino Estevez Delgado , Joaquin Estevez Delgado , Nadiezhda Montelongo Garcia , Modesto Pineda Duran

As the interior density of a neutron star can become very high, it has been expected and discussed that quark matter may exist inside it. To describe the transition from hadron to quark phases (and vice versa), there are mainly two methods;…

High Energy Astrophysical Phenomena · Physics 2017-03-29 Takahide Kambe , Tetsuya Katayama , Koichi Saito

The existence of quark matter inside the cores of heavy neutron stars is a possibility which can be probed with modern astrophysical observations. We use an (axial)vector meson extended quark-meson model to describe quark matter in the core…

Nuclear Theory · Physics 2022-05-25 Péter Kovács , János Takátsy , Jürgen Schaffner-Bielich , György Wolf

Using the Color-Dielectric model to describe quark confinement, including strange quarks and accounting for beta--equilibrium, we get masses for a static neutron star in the range $1.3\leq M/M_{\odot}\leq 1.54 $ for a radius $R\approx 9$…

Nuclear Theory · Physics 2009-10-28 A. Drago , U. Tambini , M. Hjorth-Jensen

We report results for the interaction measure, pressure and energy density for nonzero temperature QCD with 2+1 flavors of improved staggered quarks. In our simulations we use a Symanzik improved gauge action and the Asqtad $O(a^2)$…

High Energy Physics - Lattice · Physics 2008-11-26 C. Bernard , T. Burch , C. DeTar , Steven Gottlieb , L. Levkova , U. M. Heller , J. E. Hetrick , R. Sugar , D. Toussaint

The properties of hadron-quark hybrid stars are studied when the quark phase is described in terms of a local SU(3) Nambu--Jona-Lasinio (NJL) model taking into account the contribution of the vector and axial-vector interaction between the…

Nuclear Theory · Physics 2022-08-09 G. B. Alaverdyan

We constrain the equation of state of quark stars within the Bayesian statistical approach using the mass and radius measurements of PSR J0030+0451 from NICER. Three types of bag models, with and without non-zero finite quark mass and/or…

High Energy Astrophysical Phenomena · Physics 2021-08-19 Ang Li , Zhi-Qiang Miao , Jin-Liang Jiang , Shao-Peng Tang , Ren-Xin Xu

We investigate the properties of mixed stars formed by hadronic and quark matter in $\beta$-equilibrium described by appropriate equations of state (EOS) in the framework of relativistic mean-field theory. We use the non- linear Walecka…

Nuclear Theory · Physics 2009-11-10 D. P. Menezes , C. Providencia

The highlights and main results of this work can be summarized as follows : (1) The energy per nucleon of cold nuclear matter, derived by us using chiral sigma model, is in good agreement with the preliminary estimates inferred from…

High Energy Physics - Phenomenology · Physics 2008-02-03 Pradip Kumar Sahu

We investigate a simple holographic model for cold and dense deconfined QCD matter consisting of three quark flavors. Varying the single free parameter of the model and utilizing a Chiral Effective Theory equation of state (EoS) for nuclear…

High Energy Astrophysical Phenomena · Physics 2019-01-30 Eemeli Annala , Christian Ecker , Carlos Hoyos , Niko Jokela , David Rodríguez Fernández , Aleksi Vuorinen

We analyze families of hybrid equations of state of cold QCD matter, which combine input from gauge/gravity duality and from various ab initio methods for nuclear matter at low density, and predict that all neutron stars are fully hadronic…

High Energy Physics - Phenomenology · Physics 2022-04-20 Niko Jokela , Matti Järvinen , Jere Remes