arXiv subjects

Ricardo Luciano Sonego Farias

Publications and source records attributed to Ricardo Luciano Sonego Farias.

4 recordsLinked to original sources

arXiv2026

Many-body effects on dense matter with hyperons at finite temperature

In this work, we present the first extension of the Many-Body Forces (MBF) Model to finite temperature. The MBF Model describes nuclear matter in a relativistic quantum hadrodynamics formalism that takes many-body forces into account through a field dependence of the nuclear interaction coupling constants. Assuming nuclear matter to be charge neutral, beta-equilibrated, and populated by the baryon octet, electrons, muons, and neutrinos, we explore the parameter of the model that controls many-body forces, three different hyperon coupling schemes (also introduced here for the first time in the MBF Model), and temperature effects to describe basic properties of nuclear matter, including the speed of sound, compressibility, and adiabatic index. We also investigate the mass-radius relation of neutron and protoneutron stars by solving the Tolman-Oppenheimer-Volkoff equations at zero and finite temperature, including scenarios with fixed entropy per baryon and lepton fraction. We find that different hyperon coupling schemes soften the equation of state to different degrees, requiring different degrees of many-body force effects to reproduce observations, although they are never zero. Multidimensional tables with our results are available in the CompOSE repository, ready to be used in astrophysical simulations.

nucl-th↗

arXiv2026

Quantifying uncertainty in the neutron-star equation of state using point estimates and posterior distributions

We investigate uncertainty quantification for the neutron-star equation of state (EOS) by comparing point-estimation and distributional inference approaches using the same Chebyshev and piecewise-linear parameterizations. We combine neutron-star mass--radius and gravitational-wave tidal-deformability information within Bayesian, multilayer-perceptron (MLP), and normalizing-flow frameworks. Although the methods yield similar mean EOS behavior, the deterministic MLP produces substantially narrower uncertainty bands at high densities. We show that this behavior is associated with the point-estimation objective, which maps degenerate solutions toward the conditional mean rather than representing the full parameter posterior. By contrast, the normalizing flow yields distributions more consistent with the Bayesian inference. Our results demonstrate that reliable uncertainty quantification of the high-density EOS requires methods that represent conditional probability distributions rather than only point estimates.

astro-ph.HE↗

arXiv2024

Approaching the conformal limit of quark matter with different chemical potentials

We study in detail the influence of different chemical potentials (baryon, charged, strange, and neutrino) on how and how fast a free gas of quarks in the zero-temperature limit reaches the conformal limit. We discuss the influence of non-zero masses, the inclusion of leptons, and different constraints, such as charge neutrality, zero-net strangeness, and fixed lepton fraction. We also investigate for the first time how the symmetry energy of the system under some of these conditions approaches the conformal limit. Finally, we briefly discuss what kind of corrections are expected from perturbative QCD as one goes away from the conformal limit.

hep-ph↗

arXiv2023

Equations of State for Dense Matter and Astrophysical Constraints

This conference proceeding presents an overview of the modern approaches in the study of baryonic matter at high densities, focusing on the use of online repositories such as CompOSE and MUSES for the calculation of neutron star properties. In this context, relevant astrophysical constraints for the equations of state (mass-radius relation, speed of sound, tidal deformability) are discussed.

astro-ph.HE↗