arXiv subjects

Marcelo D. Alloy

Publications and source records attributed to Marcelo D. Alloy.

7 recordsLinked to original sources

arXiv2025

Bayesian Analysis of Non-extensive Parameters in Au-Au Collisions

In this work, a Bayesian statistical framework is employed to analyze particle yield ratios in Au-Au collisions, utilizing Non-Extensive Statistics (NES). Through Markov Chain Monte Carlo (MCMC) sampling, we systematically estimate key parameters, including the non-extensive factor $q$, temperature $T$, and chemical potential $μ$. Our analysis confirms previous findings highlighting the suitability and robustness of Bayesian methods in describing heavy-ion collision data. A subsequent Bayes factor analysis does not provide definitive evidence favoring an Excluded Volume Hadron Resonance Gas (EV-HRG) model over the simpler NES approach. Overall, these results suggest that combining NES with Bayesian inference can effectively model particle distributions and improve parameter estimation accuracy, demonstrating the potential of this approach for future studies on relativistic nuclear interactions.

hep-ph↗

arXiv2025

Constraining the Generalized Tolman-Oppenheimer-Volkoff (GTOV) equation with Bayesian analysis

In this work, we constrain the values of the parameters of the Generalized Tolman-Oppenheimer-Volkoff (GTOV) equation through Bayesian inference. We use the mass and radius data from the Neutron Star Interior Composition Explorer (NICER) for PSR J0740$+$6620 and PSR J0030$+$0451, as well as the mass, radius, and dimensionless tidal deformability from the gravitational wave (GW) events GW190814 and GW170817. We use two distinct parameterizations of the extended non-linear Walecka model (eNLW) with and without hyperons. The GTOV employed for the study contains additional free parameters with different physical motivations. Two possible scenarios are considered in our analysis: conservative and speculative. In the first case, we take into account the most reliable neutron star (NS) data from NICER and the GW170817 event. In the second case, we consider the possibility that the compact object with a mass of $2.54 M_{\odot}$ in the GW190814 event is an NS. Our findings show significant improvements in the physical quantities analyzed, leading to better agreement with the observational data compared to the results obtained using the TOV equation.

astro-ph.HE↗

arXiv2019

Driving upside-down in a circular track

In this article, we point out an interesting solution for the dynamics of a racecar in a banked circular track with banking angle well over 90o. We call this track configuration an Inverted Track, at which a racecar can drive partially upside-down. We show an experimental setup where we made a toy car to circulate upside-down held only by its friction to the track. We discuss the viability to perform the abovementioned stunt with a real racecar in terms of the velocities required, dimensions of the track and safety; provided a passionate motorsport related company to commission it. For most racecars, the aerodynamic down-force is significant and it is included in our analysis.

physics.pop-ph↗

arXiv2019

Hadron-quark phase transition: the QCD phase diagram and stellar conversion

Different extensions of the Nambu-Jona-Lasinio model, known to satisfy expected QCD chiral symmetry aspects, are used to investigate a possible hadron-quark phase transition at zero temperature and to build the corresponding binodal sections. We have shown that the transition point is very sensitive to the model parameters and that both pressure and chemical potential increase drastically with the increase of the vector interaction strength in the quark sector. Within the same framework, the possibility of quark and hybrid star formation is analyzed. The same conclusions drawn before with respect to the coexistence pressure and chemical potentials are reinforced. We conclude that even if a transition from a metastable hadronic star to a quark star is thermodinamically possible, it is either energetically forbidden or gives rise to a blackhole. Nevertheless, conversions from metastable to hybrid stars are possible, but the mass difference between both compact objects is very small, never larger than 0.2 M$_\odot$.

astro-ph.HE↗

arXiv2016

Maxwell equation violation by density dependent magnetic fields in neutron stars

We show that the widely used density dependent magnetic field prescriptions, necessary to account for the variation of the field intensity from the crust to the core of neutron stars violate one of the Maxwell equations. We estimate how strong the violation is when different equations of state are used and check for which cases the pathological problem can be cured.

astro-ph.HE↗

arXiv2014

Mass radius relation of compact stars in the braneworld

The braneworld scenario, based on the fact that the four dimension space-time is a hyper-surface of a five dimensional manifold, was shown to deal in a satisfactory way with the hierarchy problem. In this work we study macroscopic stellar properties of compact stars from the braneworld point of view. Using neutron star equations of state, we test the possibility of extra dimensions by solving the brane Tolman-Oppenheimer-Volkoff equations obtained for three kinds of possible compact objects: hadronic, hybrid and quark stars. By comparing the macroscopic solutions with observational constraints, we establish a brane tension lower limit and the value for which the Tolman-Oppenheimer-Volkoff equations in the braneworld converge to the usual Tolman-Oppenheimer-Volkoff equations.

nucl-th↗

arXiv2012

The Inner Crust and its Structure

In this chapter we discuss some possible physical pictures that describe the constitution of the inner crust of compact objects. Different relativistic models both with constant couplings and density dependent ones are used. We calculate the liquid-gas phase transition in asymmetric nuclear matter from the thermodynamic and dynamic instabilities. The equations of state used to describe the crust are related to the crust-core transition properties. Cold and warm pasta phases with and without alpha particles are constructed. The influence of the pasta phase and its internal structure on the diffusion coefficients associated with Boltzman transport equations used to simulate the evolution of protoneutron stars are shown. Finally, the possible existence of bare quark stars and the effects of strong magnetic fields on quark matter are considered. Open questions are pointed out.

nucl-th↗