V. Dexheimer

Proto-Neutron and Neutron Stars in a Chiral SU(3) Model

A hadronic chiral SU(3) model is applied to neutron and proto-neutron stars, taking into account trapped neutrinos, finite temperature, and entropy. The transition to the chirally restored phase is studied, and global properties of the stars such as minimum and maximum masses and radii are calculated for different cases. In addition, the effects of rotation on neutron star masses are included, and the conservation of baryon number and angular momentum determines the maximum frequencies of rotation during the cooling.

Novel approach to modeling hybrid stars

We extend the hadronic SU(3) nonlinear sigma model to include quark degrees of freedom. The choice of potential for the deconfinement order parameter as a function of temperature and chemical potential allows us to construct a realistic phase diagram from the analysis of the order parameters of the system. These parameters are the chiral condensate for the chiral symmetry restoration, and the scalar field PHI (as an effective field related to the Polyakov loop) for the deconfinement to quark matter. Besides reproducing lattice QCD results, for zero and low chemical potential, we are in agreement with neutron-star observations for zero temperature.

Hybrid stars in a strong magnetic field

We study the effects of high magnetic fields on the particle population and equation of state of hybrid stars using an extended hadronic and quark SU(3) non-linear realization of the sigma model. In this model the degrees of freedom change naturally from hadrons to quarks as the density and/or temperature increases. The effects of high magnetic fields and anomalous magnetic moment are visible in the macroscopic properties of the star, such as mass, adiabatic index, moment of inertia, and cooling curves. Moreover, at the same time that the magnetic fields become high enough to modify those properties, they make the star anisotropic.

Bulk Properties of a Fermi Gas in a Magnetic Field

of the anomalous magnetic moment. We demonstrate that the resulting expressions satisfy the canonical relations, = Pk and P? = Pk MB, with M = @ =@B being the magnetization of the system. We numerically calculate the resulting pressure anisotropy for a gas of protons and a gas of neutrons and demonstrate that the inclusion of the anomalous magnetic increases the level of pressure anisotropy in both cases.

EMMI rapid reaction task force meeting on quark matter in compact stars

The recent measurement of two solar mass pulsars has initiated an intense discussion on its impact on our understanding of the high-density matter in the cores of neutron stars. A task force meeting was held from October 7-10, 2013 at the Frankfurt Institute for Advanced Studies to address the presence of quark matter in these massive stars. During this meeting, the recent observational astrophysical data and heavy-ion data was reviewed. The possibility of pure quark stars, hybrid stars and the nature of the QCD phase transition were discussed and their observational signals delineated.

MANY-BODY FORCES IN THE EQUATION OF STATE OF HYPERONIC MATTER

In this work we introduce an extended version of the formalism proposed originally by Taurines et al. that considers the effects of many-body forces simulated by non-linear self-couplings and meson-meson interaction contributions. In this extended version of the model, we assume that matter is at zero temperature, charge neutral and in beta-equilibrium, considering that the baryon octet interacts by the exchange of scalar-isoscalar (

The influence of strong magnetic fields on proto-quark stars

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Hydrodynamics with a chiral hadronic equation of state including quark degrees of freedom

,

Noncongruence of the nuclear liquid-gas and deconfinement phase transitions

\,\sigma^*

NEUTRON STARS WITH SMALL RADII—THE ROLE OF Δ RESONANCES

), vector-isoscalar (