We study the effect of electric charge in compact stars assuming that distribution is proportional to mass density. The pressure and density matter inside are large, gravitational field intense. This indicates a strong can also be present. relativistic hydrostatic equilibrium equation, i.e., Tolman-Oppenheimer-Volkoff modified order include charge. perform detailed numerical using polytropic equation state. conclude see any appreciable on phenomenology stars, fields have huge...

A generalized relativistic harmonic oscillator for spin 1∕2 particles is studied. The Dirac Hamiltonian contains a scalar $S$ and vector $V$ quadratic potentials in the radial coordinate, as well tensor potential $U$ linear $r$. Setting either or both combinations $\ensuremath{\Sigma}=S+V$ $\ensuremath{\Delta}=V\ensuremath{-}S$ to zero, analytical solutions bound states of corresponding equations are found. eigenenergies wave functions presented particular cases discussed, devoting special...

The possible existence of compact stars made absolutely stable strange quark matter---referred to as stars---was pointed out by Witten almost a quarter century ago. One the most amazing features such objects concerns ultrastrong electric fields on their surfaces, which, for ordinary matter, is around ${10}^{18}\text{ }\text{ }\mathrm{V}/\mathrm{cm}$. If matter forms color superconductor, expected strength field may increase values that exceed ${10}^{19}\text{ energy density associated with...

There is a host of alternative theories gravitation in the literature, among them $f(R,T)$ recently elaborated by Harko and collaborators. In these $R$ $T$ are respectively Ricci scalar trace energy momentum tensor. already literature series studies different forms functions as well their cosmological consequences. However, there not so far related to gravitational waves gravity. Here we consider such an issue, particular studying putative extra polarization models that can appear theories....

In this article we study the hydrostatic equilibrium configuration of neutron stars and strange stars, whose fluid pressure is computed from equations state p=ωρ5/3 p=0.28(ρ−4ℬ), respectively, with ω ℬ being constants ρ energy density fluid. We start by deriving equation for f(R,T) theory gravity, R T standing Ricci scalar trace energy-momentum tensor, respectively. Such an a generalization one obtained general relativity, latter can be retrieved certain limit theory. For f(R,T)=R+2λ...

The influence of the anisotropy in equilibrium and stability strange stars is investigated through numerical solution hydrostatic equation radial oscillation equation, both modified from their original version to include this effect. matter inside quark described by MIT bag model state. For two different kinds local anisotropic σ = pt−pr are considered, where pt pr respectively tangential pressure: one that null at star's surface defined pr(R) 0, nonnull surface, namely, σs 0 ≠ 0. In case...

In this work we investigate the equilibrium configurations of white dwarfs in a modified gravity theory, na\-mely, $f(R,T)$ gravity, for which $R$ and $T$ stand Ricci scalar trace energy-momentum tensor, respectively. Considering functional form $f(R,T)=R+2\lambda T$, with $\lambda$ being constant, obtain hydrostatic equation theory. Some physical properties dwarfs, such as: mass, radius, pressure energy density, as well their dependence on parameter are derived. More massive larger found...

In this work we study the contribution of isoscalar tensor coupling to realization pseudospin symmetry in nuclei. Using realistic values for strength, show that reduces noticeably splittings, especially single-particle levels near Fermi surface. By using an energy decomposition changes these splittings come by mainly through induced lower radial wave function low-lying partners, and expectation value pseudospin-orbit term surface partners. This allows us confirm conclusion already reached...

The hydrostatic equilibrium and the stability against radial perturbation of charged strange quark stars composed a perfect fluid are studied. For this purpose, it is considered that follows MIT bag model equation state charge distribution power-law. investigated through numerical solutions Tolman-Oppenheimer-Volkoff Chandrasekhar's pulsation equation, being these equations modified from their original form to include electrical charge. In order appreciably affect stellar structure, found...

Pseudospin symmetry in nuclei is investigated by solving the Dirac equation with Woods-Saxon scalar and vector radial potentials, studying correlation of energy splittings pseudospin partners nuclear potential parameters. The interaction related to a pseudospin-orbit term that arises Schroedinger-like for lower component spinor. We show contribution from this large. near degeneracy results significant cancellation among different terms equation, manifesting dynamical character nucleus....

Pseudospin symmetry in nuclei is investigated considering the Dirac equation with a Lorentz structured Woods-Saxon potential. The isospin correlation of energy splittings pseudospin partners nuclear potential parameters studied. We show that, an isotopic chain, better realized for neutrons than protons. This behavior comes from balance effects among central parameters. In general, we found asymmetry interaction, opposed to spin-orbit interaction which quasi-isospin symmetric.

We solve the generalized relativistic harmonic oscillator in 1+1 dimensions, i.e., including a linear pseudoscalar potential and quadratic scalar vector potentials which have equal or opposite signs. consider positive negative discuss detail their bound-state solutions for fermions antifermions. The main features of these bound states are same as ones three-dimensional states. found zero related to spin pseudospin symmetry Dirac equation 3+1 dimensions. show how charge conjugation $\gamma^5$...

SGR 0418$+$5729 is a “Rosetta Stone” for deciphering the energy source of Soft Gamma Ray Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs). We present model based on canonical physics astrophysics SGRs AXPs powered by massive highly magnetized rotating white dwarfs (WDs), in total analogy with pulsars neutron stars (NSs). predict lower limit its spin-down rate, $\dot{P}~\geq~L_{\rm X} P^3/$(4$\pi^2 I$) $=$ 1.18 $\times$ 10$^{-16}$, where $I$ moment inertia WD. show that occurrence glitch...

In this work we investigate neutron stars (NS) in $f(\mathcal{R,T})$ gravity for the case $R+2\lambda\mathcal{T}$, $\mathcal{R}$ is Ricci scalar and $\mathcal{T}$ trace of energy-momentum tensor. The hydrostatic equilibrium equations are solved considering realistic state (EsoS). NS masses radii obtained subject to a joint constrain from massive pulsars event GW170817. parameter $\lambda$ needs be negative as previous studies, however found minimum value it. should $|\lambda|\lesssim0.02$...

This work analyses the hydrostatic equilibrium configurations of strange stars in a non-minimal geometry-matter coupling (GMC) theory gravity. Those are made quark matter, whose distribution is governed by MIT equation state. The GMC described following gravitational action: $f(R,L)=R/2+L+\sigma RL$, where $R$ represents curvature scalar, $L$ matter Lagrangian density, and $\sigma$ parameter. When considering this theory, become larger more massive. In particular, when $\sigma=50$ km$^2$,...

Spin and pseudospin symmetries in the spectra of nucleons antinucleons are studied a relativistic mean-field theory with scalar vector Woods-Saxon potentials, which strength latter is allowed to change. We observe that, for antinucleons, spin symmetry perturbative nature it almost an exact physical region antinucleons. The opposite situation found case, better realized than but dynamical cannot be viewed way either or This shown by computation spin-orbit pseudospin-orbit couplings selected...

We derive the node structure of radial functions which are solutions Dirac equation with scalar $S$ and vector $V$ confining central potentials, in conditions exact spin or pseudospin symmetry, i.e., when one has $V=\ifmmode\pm\else\textpm\fi{}S+C$, where $C$ is a constant. show that for symmetry same as potentials go to zero at infinity but reversed. obtain important result it possible have positive energy bound any shape, including naturally those used hadron physics, from nuclear quark...

In this work, we analyze the effect of charge in compact stars considering limit maximum amount they can hold. We find that global balance forces allows a huge (~ 10^{20} Coulomb) to be present neutron star producing very high electric field 10^{21} V/m). have studied particular case polytropic equation state and assumed distribution is proportional mass density. The charged large radius as should expect due repulsive Coulomb force with M/R ratio increasing charge. goes up ~ 10 M_sun which...

We show that the conditions which originate spin and pseudospin symmetries in Dirac equation are same produce equivalent energy spectra of relativistic spin-1/2 spin-0 particles presence vector scalar potentials. The conclusions do not depend on particular shapes potentials can be important different fields physics. When both spherical, these for isospectrality imply spin-orbit Darwin terms either upper component or lower spinor vanish, making it equivalent, as far is concerned, to a state....

We estimate the vector interaction strength of Polyakov-Nambu-Jona-Lasinio (PNJL) parametrizations, assuming that its transition curves should be as close possible recently studied RMF-PNJL hadron-quark phase diagrams. Such diagrams are obtained matching relativistic mean-field hadronic models, and PNJL quark ones. By using this method we found for magnitude interaction, often treated a free parameter, range 7.66 GeV$^{-2}\lesssim G_V \lesssim 16.13$ GeV$^{-2}$, or equivalently, $1.52...

Massive, highly magnetized white dwarfs with fields up to 109 G have been observed and theoretically used for the description of a variety astrophysical phenomena. Ultramagnetized uniform interior 1018 recently purported obey new maximum mass limit, Mmax ≈ 2.58 M☉, which largely overcomes traditional Chandrasekhar value, MCh 1.44 M☉. Such larger limit would make these objects viable candidates explanation superluminous population Type Ia supernovae. We show that several macro micro physical...

Abstract Anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs) are some of the most interesting groups that have been intensively studied in recent years. They understood as neutron stars (NSs) with super-strong magnetic fields, namely B ≳ 1014 G. However, last two years SGRs low fields ∼ (1012–1013) G detected. Moreover, three fast very white dwarfs (WDs) also observed Based on these new pulsar discoveries, we compare contrast dipole moment, characteristic ages, steady...

An effective field theory is used to give a model-independent description of Compton scattering at energies comparable the pion mass. The amplitudes for on proton and deuteron, calculated fourth order in small momenta chiral perturbation theory, contain four undetermined parameters that are one-to-one correspondence with nucleon polarizabilities. These polarizabilities extracted from fits data elastic photon hydrogen deuterium. For we find: αp=(12.1±1.1)−0.5+0.5×10−4 fm3,...