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Celso C. Barros Jr

Publications and source records attributed to Celso C. Barros Jr.

11 recordsLinked to original sources

Kiselev black strings: the charged rotating solutions

We investigate the properties of a charged rotating black string immersed in a Kiselev anisotropic fluid in anti-de Sitter (AdS) spacetime. The Einstein-Maxwell equations with an anisotropic stress-energy tensor and cosmological constant are analyzed and solved exactly. In this work, we calculate the Kretschmann scalar, obtaining a consistent result that agrees with the existing literature in the absence of charge and fluid. The rotating solution is obtained by applying a coordinate transformation on time and angular coordinates. The event horizon associated with specific values of the equation of state parameter $w_q$ is studied. The results show an important influence of the fluid parameters $N_{q}$ and $w_{q}$, the charge parameter $Q$, and the rotation parameter $a$ on the size of the black string horizon. In addition, we determine the conditions for the existence of closed timelike curves (CTCs) and compute the conserved charges, such as mass, angular momentum, and electric charge of the black string. Utilizing the Klein-Gordon equation, we employ the quantum particle tunneling approach to obtain the probability of charged scalar particles tunneling across the event horizon. We obtain the correspondent Hawking temperature as a consequence. Furthermore, we examine the thermodynamic properties, including entropy and heat capacity, to assess the effects of the quintessence field and charge on the black string. The results include particular cases such as the Lemos black string, providing a broader view of black string configurations in AdS spacetime.

gr-qc↗

Spin-0 bosons near rotating stars

In this work we study the effects of rotating stars on the behavior of bosons close to their surfaces. For this task, metrics determined by the rotation of these stars will be taken into account. We will consider the Klein-Gordon equation in the Hartle-Thorne metric and in the one proposed by Berti et al. by considering some kinds of stars. Pions and Higgs bosons will be investigated as examples. By solving the equations, the main effect that may be observed is a rotational phase, $δ_R$, that depends on the angular momentum of the star, $J$, in the wave function of the boson. Corrections of higher orders in $J$ are also investigated.

gr-qc↗

Low energy Eta-baryon interaction

The $η$-Baryon interactions at low energies are studied in a model based in effective chiral Lagragians that take into account baryons of spin 1/2 and spin 3/2 in the intermediate states. The interacting baryons to be considered in this work are $B= N, Λ, Σ, Ξ$. We calculate the expected total and differential cross sections, phase-shifts and polarizations in the center-of-mass frame of reference for each reaction.

hep-ph↗

Fluctuations in the pasta phase

Baryonic matter close to the saturation density is very likely to present complex inhomogeneous structures collectively known under the name of pasta phase. At finite temperature, the different geometric structures are expected to coexist, with potential consequences on the neutron star crust conductivity and neutrino transport in supernova matter. In the framework of a statistical multi-component approach, we calculate the composition of matter in the pasta phase considering density, proton fraction, and geometry fluctuations. Using a realistic energy functional from relativistic mean field theory and a temperature and isospin dependent surface tension fitted from Thomas-Fermi calculations, we show that different geometries can coexist in a large fraction of the pasta phase, down to temperatures of the order of the crystallization temperature of the neutron star crust. Quantitative estimates of the charge fluctuations are given.

nucl-th↗

Low energy pion-$Λ_b$ interaction

In this work we study the low energy pion-$Λ_b$ interaction considering effecective chiral Lagrangians that include pions, baryons and the corresponding resonances. Interactions mediated by a $σ$ meson exchange are also considered. The scattering amplitudes are calculated and then we determine the angular distributions and polarizations.

hep-ph↗

Polarization in low energy kaon-hyperon interaction

In this paper, we study the low energy kaon-hyperon interaction considering effective chiral Lagrangians that include kaons, $σ$ mesons, hyperons and the corresponding resonances. The scattering amplitudes are calculated and then we determine the angular distributions and polarizations.

hep-ph↗

Pasta fluctuations in symmetric matter at finite temperature

The equilibrium distributions of the different pasta geometries and their linear sizes are calculated from the mean field Gibbs energy functional in symmetric nuclear matter at finite temperature. The average sizes and shapes coincide approximately with the ones predicted by a standard pasta calculation in the coexisting phase approximation, but fluctuations are additionally calculated and seen to increase with temperature and baryonic density. The different pasta shapes are shown to coexist in a wide domain of density and temperature, in qualitative agreement with the findings of large scale molecular dynamics simulations, but with a much less expensive computational cost.

nucl-th↗

Low energy kaon-hyperon interaction

In this work we study the low energy kaon-hyperon interaction considering effective chiral Lagrangians that include kaons, $σ$ mesons, hyperons and the corresponding resonances. We calculate the scattering amplitudes, and then the total cross sections, angular distributions, polarizations and the $S$ and $P$ phase shifts.

hep-ph↗

Some diagrams and basic formalism to the low energy kaon-hyperon interaction

In this work the low energy kaon-hyperon interaction is studied with nonlinear chiral invariant Lagragians considering kaons, hyperons, and the corresponding resonances in the intermediate states. We show the basic formalism to calculate the total cross sections, angular distributions, and some diagrams of interest.

hep-ph↗

Dirac equation and the Melvin Metric

A relativistic wave equation for spin 1/2 particles in the Melvin space-time, a space-time where the metric is determined by a magnectic field, is obtained. The effects of very intense magnetic fields in the energy levels, as intense as the ones expected to be produced in ultra-relativistic heavy-ion collisions, are investigated.

hep-th↗

Hadronic Matter in the Robertson-Walker Metric and the Early Universe

In this work, the Friedman equations for hadronic matter in the Robertson-Walker metric in the early Universe are obtained. We consider the hadronic phase, formed after the hadronization of the quark-gluon plasma, that means times from 10^{-6}s to 1s. The set of equations is derived and the behavior of the system is studied considering one approximate analytical solution.

nucl-th↗