I. Vidaña

Constraints on the symmetry energy and neutron skins from experiments and theory

The symmetry energy contribution to the nuclear equation of state impacts various phenomena in nuclear astrophysics, nuclear structure, and nuclear reactions. Its determination is a key objective of contemporary nuclear physics, with consequences for the understanding of dense matter within neutron stars. We examine the results of laboratory experiments that have provided initial constraints on the nuclear symmetry energy and on its density dependence at and somewhat below normal nuclear matter density. Even though some of these constraints have been derived from properties of nuclei while others have been derived from the nuclear response to electroweak and hadronic probes, within experimental uncertainties-they are consistent with each other. We also examine the most frequently used theoretical models that predict the symmetry energy and its slope parameter. By comparing existing constraints on the symmetry pressure to theories, we demonstrate how contributions of three-body forces, which are essential ingredients in neutron matter models, can be determined.

Quark Deconfinement and Implications for the Radius and the Limiting Mass of Compact Stars

We study the consequences of the hadron-quark deconfinement phase transition in stellar compact objects when finite-size effects between the deconfined quark phase and the hadronic phase are taken into account. We show that above a threshold value of the central pressure (gravitational mass) a neutron star is metastable to the decay (conversion) to a hybrid neutron star or to a strange star. The mean lifetime of the metastable configuration dramatically depends on the value of the stellar central pressure. We explore the consequences of the metastability of massive neutron stars and of the existence of stable compact quark stars (hybrid neutron stars or strange stars) on the concept of the limiting mass of compact stars. We discuss the implications of our scenario for the interpretation of the stellar mass and radius extracted from the spectra of several X-ray compact sources. Finally, we show that our scenario implies, as a natural consequence, a two-step process that is able to explain the inferred delayed connection between supernova explosions and gamma-ray bursts (GRBs), giving also the correct energy to power GRBs.

Hyperon-hyperon interactions and properties of neutron star matter

We present results from Brueckner-Hartree-Fock calculations for

Estimation of the effect of hyperonic three-body forces on the maximum mass of neutron stars

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Strange nuclear matter within Brueckner-Hartree-Fock theory

-stable neutron star matter with nucleonic and hyperonic degrees of freedom, employing the most recent parametrizations of the baryon-baryon interaction of the Nijmegen group. It is found that the only strange baryons emerging in

Do hyperons exist in the interior of neutron stars

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Dynamically generated open-charm baryons beyond the zero-range approximation

-stable matter up to total baryonic densities of 1.2

Constraining the nuclear equation of state at subsaturation densities

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Nuclear symmetry energy and the r-mode instability of neutron stars

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Nuclear symmetry energy and the role of the tensor force

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