International Journal of Modern Physics: Conference Series

Walter Greiner (29 October 1935 - 6 October 2016) was a German theoretical physicist. His scientific research interests include the thematic areas of atomic physics, heavy ion physics, nuclear physics, elementary particle physics (particularly quantum electrodynamics and quantum chromodynamics). He is most known in Germany for his series of books in theoretical physics, but he is also well known around the world. Greiner was born on October 29, 1935, in Neuenbau, Sonnenberg, Germany. He studied physics at the University of Frankfurt (Goethe University in Frankfurt Am Main), receiving in this institution a BSci in physics and a Master’s degree in 1960 with a thesis on plasma-reactors, and a PhD in 1961 at the University of Freiburg under Hans Marshal, with a thesis on the nuclear polarization in $\mu$-mesic atoms. During the period of 1962 to 1964 he was assistant professor at the University of Maryland, followed by a position as research associate at the University of Freiburg, in 1964. Starting in 1965, he became a full professor at the Institute for Theoretical Physics at Goethe University until 2003. Greiner has been a visiting professor to many universities and laboratories, including Florida State University, the University of Virginia, the University of California, the University of Melbourne, Vanderbilt University, Yale University, Oak Ridge National Laboratory and Los Alamos National Laboratory. In 2003, with Wolf Singer, he was the founding Director of the Frankfurt Institute for Advanced Studies (FIAS), and gave lectures and seminars in elementary particle physics. He died on October 6, 2016 at the age of 80.

Walter Greiner was an excellent teacher, researcher, friend. And he was a great supporter of the series of events known by the acronyms IWARA - International Workshop on Astronomy and Relativistic Astrophysics, STARS - Caribbean Symposium on Cosmology, Gravitation, Nuclear and Astroparticle Physics, and SMFNS - International Symposium on Strong Electromagnetic Fields and Neutron Stars. Walter Greiner left us. But his memory will remain always alive among us who have had the privilege of knowing him and enjoy his wisdom and joy of living.

The present status of the pseudo-complex General Relativity is presented. The pcGR includes many known theories with a minimal length. Restricting to its simplest form, an energy-momentum tensor is added at the right hand side of the Einstein equations, representing a dark energy, related to vacuum fluctuations. We use a phenomenological ansatz for the density and discuss observable consequences: Quaisperiodic Oscillations (QPO), effects on accretion disks and gravitational waves.

Gravitational theories outside standard general relativity have been drawing increased attention over the past several years, mostly due to the lack of direct observational evidence of dark matter. With some recent very high level dark matter searches continuing, and the parameter space to search decreasing has lead to a new interest in rethinking gravity at the largest of scales. As an alternative gravitational theory, conformal gravity has enjoyed much of the success of Modified Newtonian Dynamics (MOND) in predicting phenomenology, but differs dramatically in its initial construction. In this work, we explore some recent advances in conformal gravity, which help to build the case for support of such an alternative theory. Here, we highlight conformal gravity’s success in fitting new rotation curves, its ability to explain velocity dispersions in clusters, the initial steps towards gravitational lensing and finally, some preliminary work on explaining universal centripetal acceleration trends in galaxies.

A new tetrad is introduced within the framework of geometrodynamics for non-null electromagnetic fields. This tetrad diagonalizes the electromagnetic stress-energy tensor and allows for maximum simplification of the expression of the electromagnetic field. The Einstein-Maxwell equations will also be simplified. New group isomorphisms are proved. The local group of electromagnetic gauge transformations is isomorphic to the new group LB1. LB1 is the group of local tetrad transformations comprised by SO(1,1) plus two different kinds of discrete transformations. The local group of electromagnetic gauge transformations is also isomorphic to the local group of tetrad transformations LB2, which is SO(2), as well. Therefore, we proved that LB1 is isomorphic to LB2. These group results amount to proving that the no-go theorems of the sixties like the S. Coleman- J. Mandula, the S. Weinberg or L. ORaifeartagh versions are incorrect. Not because of their internal logic, but because of the assumptions made at the outset of all these versions. These new tetrads are useful in astrophysics spacetime evolution algorithms since they introduce maximum simplification in all relevant objects, specially in stress-energy tensors.

We propose a gravitation theory in 4 dimensional space-time obtained by compacting to 4 dimensions the five dimensional topological Chern-Simons theory with the gauge group SO(1,5) or SO(2,4) – the de Sitter or anti-de Sitter group of 5-dimensional space-time. In the resulting theory, torsion, which is solution of the field equations as in any gravitation theory in the first order formalism, is not necessarily zero. However, a cosmological solution with zero torsion exists, which reproduces the Lambda-CDM cosmological solution of General Relativity. A realistic solution with spherical symmetry is also obtained.

The gravitational wave, through the strongly magnetized plasma surrounding the neutron stars, in the $z$-direction, deforms plasma particle rings in ellipses, alternating axes periodically along the direction of the magnetic field ($x$-axis) and of the $y$-axis. The uniform field leads to a modulation of the magnetic field, which results in magnetic pressure gradients (magneto-acoustic mode) or in the shear of the magnetic field lines (Alfvén mode). The gravitational wave drives MHD modes and transfers energy to the plasma, can become an important alternative process for the acceleration of baryons to high Lorentz factors observed in short GRBs. The total amount of energy that is transferred from the gravitational wave to the plasma is estimated ($\simeq 10^{40}$J - $10^{41}$ J), with $\gamma \simeq 10^2$. We compare our results with previously obtained results by other works.

The luminosity function (LF) statistics applied in data of GRBs detected by GBM/Fermi and BAT/Swift is the theme approached in this work. The LF is a strong statistical tool to extract useful information from astrophysical samples, and the key point of this statistical analysis is in the detector sensitivity, where we have performed careful analysis. We produced, by LF statistics, the GRB predicted distributions of: peak ux N(Fpk), redshift N(z) and peak luminosity N(Lpk). We also used different GRB rates. We performed a comparison between the distributions predicted and observed (with and without redshifts), where we had to build a list with more then 250 GRBs with known redshifts. We estimated the effects of the Malmquist bias in all samples, and we looked for a correlation between the isotropic luminosity and the Band peak spectral energy.

The phenomenon that originates gamma ray bursts (GRBs) remains undefined. In this work the conversion of a hadronic star into a quark star is discussed as one of the possible causes of GRBs. Effective models are used to describe the compact stars and to obtain their equations of state. Macroscopic properties, such baryonic and gravitational masses, of both types of stars are then obtained from the solution of the hydrostatic equilibrium equations. The relation between this values allows to calculate the amount of energy possibly released in this process. The obtained results are then compared to actual GRB observational data, and are within the observational order of magnitude.

In both WMAP and Planck observations on the temperature anisotropy of cosmic microwave background (CMB) radiation a number of large-scale anomalies were discovered in the past years, including the CMB parity asymmetry in the low multipoles. By defining a directional statistics, we find that the CMB parity asymmetry is directional dependent, and the preferred axis is stable, which means that it is independent of the chosen CMB map, the definition of the statistic, or the CMB masks. Meanwhile, we find that this preferred axis strongly aligns with those of the CMB quadrupole, octopole, as well as those of other large-scale observations. In addition, all of them aligns with the CMB kinematic dipole, which hints to the non-cosmological origin of these directional anomalies in cosmological observations.

Measuring the imprint of primordial gravitational waves in the cosmic microwave background (CMB) polarisation field is one of the main goals in modern cosmology. However, the so called $B$-mode polarisation can be generated by different sources besides the primary one predicted by inflationary theories, known as secondary $B$-mode signal. Among them, CMB lensing and astrophysical foregrounds play an important role. Moreover, a partial sky analysis leads to a leakage between $E$-modes and $B$-modes. In this article, we use the well known Minkowski functionals (MF) statistics to study the significance of this leakage in the CMB lensing $B$-mode signal. We find that the MF can detect the $E$-to-$B$ leakage contamination, thus it should not be neglected in future CMB data analysis.

One of the great mysteries in current physics is the nature of dark matter. Arguments are brought forward to consider a form dark matter, manifested as a broken local dual symmetry of a bimetric spin-2 theory in the Fierz representation.

We investigate the dark matter problem in the context of Pseudo-complex General Relativity. A form of gravitational dark matter has recently been studied, the mimetic dark matter, which is a scalar tensor extension for gravity where the conformal degree of freedom is isolated in a covariant way. For such, we perform a combination of both approaches to reveal non trivial results even in the absence of matter. Solutions for different scenarios and possible interpretations are presented.

We review and emphasize the importance of the Satellite Test of the Equivalence Principle (STEP) in probing one of the most successful and popular alternative theories to dark matter known as Modified Newtonian Dynamics (MOND), on Earth. This would be achieved with no modification of STEP’s current design and sensitivity and if MOND exists STEP could in principle easily detect it.

Let’s discuss some points, concerning to the cosmic censorship conjecture for the Kantowski-Sachs model.

Using the Helmholtz theorem (modified to time-varying vector fields) the Jefimenko’s gravito-electromagnetic equations are deduced. Newton’s gravitational field emerges as a particular case when an action at a distance theory is considered.

A large class of modified theories of gravity used as models for dark energy predict a propagation speed for gravitational waves which can differ from the speed of light. This difference of propagations speeds for photons and gravitons has an impact in the emission of gravitational waves by binary systems. Thus, we revisit the usual quadrupolar emission of binary system for an arbitrary propagation speed of gravitational waves and obtain the corresponding period decay formula. We then use timing data from the Hulse-Taylor binary pulsar and obtain that the speed of gravitational waves can only differ from the speed of light at the percentage level. This bound places tight constraints on dark energy models featuring an anomalous propagations speed for the gravitational waves.

The gravity wave detector at the University of Western Australia was based on a bending flap of $0.45kg$ tuned near the fundamental resonant frequency of a $1.5ton$ resonant-bar of $710Hz$ at a temperature of $5K$. The displacement of the bending flap was monitored with a $9.5GHz$ superconducting re-entrant cavity transducer. The performance of the transducer is related to the development of a low noise microwave pump oscillator to drive the transducer. This work studies the influence of the frequency tracking noise of Niobè. It had a burst sensitivity of $h\approx 7\times 10^{-19}$ with a long term operation from 1993 to early 1998. It had the lowest observed noise temperature. Using the characteristics of the detector, NIOBÈ should had reached a much better sensitivity that the one measure. It seems that the noise introduced in the system by the frequency tracking device was not taken into account at the time of operation, this noise gives a value of $\approx 2.5\times 10^{-18}m/{(Hz)}^{-1/2}$, what is the value that limited the detector sensitivity to the one measured at the time of operation.

A experiment to measure the velocity of gravity is been planned. In order to achieve a reasonable signal in the detector, a very massive quadrupole mass is put to rotate at a very high rotation speed. In order to maximize the signal, the product mass and rotation radius squared much be as higher as possible. This work test a composite mass-quadrupole geometries in Finite Element Modeling (FEM) with the goal to maximize the signal

A experiment to measure the velocity of gravity is been planned. In order to achieve a reasonable signal in the detector, a very massive quadrupole mass is put to rotate at a very high rotation speed. In order to maximize the signal, the mass much be as higher as possible. This work test mass geometries in Finite Element Modeling (FEM) with the goal to maximize the resistance to high rotation speed.

This work aims to design a magnetic suspension for an experiment to measure gravitys velocity. Such device must rotate two objects symmetrically with the greatest mass and largest radius as possible, at the speed of $500000rpm$, which means this device falls into the high-speed machines category. The guidelines and solutions proposed in this paper constitute a contribution to this class of engineering problems and were based on an extensive literature search, contacts with experts, the tutors and author’s experience, as well as on experimental results. The main solution proposed is a hybrid bearing that combines a radial passive magnetic bearing with an axial sliding bearing, here called MPS (Magnetic Passive and Sliding) bearing.

Symplectic maps are well known for preserving the phase-space volume in Hamiltonian dynamics and are particularly suited for problems that require long integration times, such as the $N$-body problem. However, when combined with a varying time-step scheme, they end up losing its symplecticity and become numerically inefficient. We address this problem by using a recursive Hamiltonian splitting based on the time-symmetric value of the individual time-steps required by the particles in the system. We present a family of 48 quasi-symplectic maps with different orders of convergence (2nd-, 4th- & 6th-order) and three time-stepping schemes: i) 16 using constant time-steps, ii) 16 using shared adaptive time-steps, and iii) 16 using hierarchical (individual) time-steps. All maps include post-Newtonian corrections up to order 3.5PN. We describe the method and present some details of the implementation.

The growth of supermassive black holes is intermittent, having periods of low accretion when no nuclear activity is seen in the center of the host galaxy. In such dormant state black holes may tidally disrupt stars scattered from the bulge to inside their influence sphere. The resulting debris are partially captured by the black hole forming a short-lived accretion disk, which produces a variable emission dubbed “tidal flare”. Some galaxies candidate to have hosted these tidal events are here considered.

White dwarf stars are the final stage of most stars, born single or in multiple systems. We discuss the identification, magnetic fields, and mass distribution for white dwarfs detected from spectra obtained by the Sloan Digital Sky Survey up to Data Release 13 in 2016, which lead to the increase in the number of spectroscopically identified white dwarf stars from 5000 to 39000. This number includes only white dwarf stars with $logg\ge 6.5$, i.e., excluding the Extremely Low Mass white dwarfs, which are necessarily the byproduct of stellar interaction.

In this work, we discuss white dwarf pulsars found recently making also reference of the possibility of some SGRs/AXPs being part of this class of pulsars. We also study the properties of very massive compact ultra magnetized white dwarfs that could be the progenitors candidates of super luminous type Ia supernovae, and also a previous stage of these white dwarf pulsars before the magnetic field decay.The structure of this ultra magnetized white dwarfs is obtained by solving the Einstein-Maxwell equations with a poloidal magnetic field in a fully general relativistic approach. The stellar interior is composed of a regular crystal lattice made of carbon ions immersed in a degenerate relativistic electron gas. We find that magnetized white dwarfs violate the standard Chandrasekhar mass limit significantly. We obtain a maximum white dwarf mass of around $2.12M_{\odot }$ with an equatorial radius $R\sim 1596$ Km, a central magnetic field of $B_c=1.74\times 10^{14}$ G and $B_s=3.6\times 10^{13}$ G at the stellar surface.

Rotating magnetized white dwarfs are studied within the framework of general relativity using Hartle’s formalism. Matter inside magnetized white dwarfs is described by an equation of state of particles under the action of a constant magnetic field which introduces anisotropic pressures. Our study is done for values of magnetic field below $10^{13}$ G - a threshold of the maximum magnetic field obtained by the cylindrical metric solution - and typical densities of WDs. The effects of the rotation and magnetic field combined are discussed, we compute relevant magnitudes such as the moment of inertia, quadrupole moment and eccentricity.

We compute models for the equation of state (EoS) of the matter in the cores of hybrid stars. Hadronic matter is treated in the non-linear relativistic mean-field approximation, and quark matter is modeled by three-flavor local and non-local Nambu−Jona-Lasinio (NJL) models with repulsive vector interactions. The transition from hadronic to quark matter is constructed by considering either a soft phase transition (Gibbs construction) or a sharp phase transition (Maxwell construction). We find that high-mass neutron stars with masses up to $2.1-2.4M_{\odot }$ may contain a mixed phase with hadrons and quarks in their cores, if global charge conservation is imposed via the Gibbs conditions. However, if the Maxwell conditions is considered, the appearance of a pure quark matter core either destabilizes the star immediately (commonly for non-local NJL models) or leads to a very short hybrid star branch in the mass-radius relation (generally for local NJL models).

The properties of the neutron star crust are crucially important for many physical processes occurring in the star. For instance, the crustal transport coefficients define the temperature evolution of accreting stars after bursts, which can be compared to observation. Furthermore, the structure of the inner crust can modify the neutrino transport through the matter considerably, significantly impacting the dynamics of supernova explosions. Therefore, we perform numerical studies of the inner crust, and among other aspects, investigate the dependence of the pasta phase on the isospin properties of the nuclear interactions. To this end we developed an efficient computer code to simulate the inner and outer crust using molecular dynamics techniques. First results of the simulations and insights into the crust-core transition are presented.

We have studied the phase transition from hadronic to quark matter inside neutron stars, we calculate the rate and emissivity for all the relevant weak interaction processes and solve the Boltzmann transport equation, considering the effect of strong interactions in the perturbative regime to the order of QCD coupling constant ${\alpha }_c$. We find that the neutrino and antineutrino emissivity is around of 10${}^{53}$ erg.

Traditional stellar structure models of non-rotating neutron stars work under the assumption that these stars are perfect spheres. This assumption of perfect spherical symmetry is not correct if the matter inside neutron stars is described by an anisotropic model for the equation of state. Certain classes of neutron stars such as Magnetars and neutron stars which contain color-superconducting quark matter cores are expected to be deformed making them oblong spheroids. In this work, we investigate the stellar structure of these deformed neutron stars by deriving stellar structure equations in the framework of general relativity. Using a non-isotropic equation of state model, we solve these structure equations numerically in two dimensions. We calculate stellar properties such as masses and radii along with pressure profiles and investigate changes from standard spherical models.

We show that nine soft gamma repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs) of the twenty three known sources can be described as rotation-powered canonical pulsars. To accomplish this we use realistic parameters of rotating neutron stars obtained from numerical integration of the self-consistent axisymmetric general relativistic equations of equilibrium. We present limits to the NS mass where the sources can be rotation-powered.

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. We then propose a simple solution that allows for the usual prescriptions to be used without violating a fundamental equation of physics.

In this work we show the results for numerical solutions of the relativistic Grad-Shafranov equation for a typical neutron star with 1.4 solar masses. We have studied the internal magnetic field considering both the poloidal and toroidal components, as well as the behavior of the field lines parametrized by the ratio between these components of the field.

In this work, we study the effects of different magnetic field configurations in neutron stars described by a many-body forces formalism (MBF model). The MBF model is a relativistic mean field formalism that takes into account many-body forces by means of a meson field dependence of the nuclear interaction coupling constants. We choose the best parametrization of the model that reproduces nuclear matter properties at saturation and also describes massive neutron stars. We assume matter to be in beta-equilibrium, charge neutral and at zero temperature. Magnetic fields are taken into account both in the equation of state and in the structure of the stars by the self-consistent solution of the Einstein-Maxwell equations. We assume a poloidal magnetic field distribution and calculate its effects on neutron stars, showing its influence on the gravitational mass and deformation of the stars.

In this work we have obtained the equation of state to the highly asymmetric dense stellar matter, using the nonlinear Walecka model in the mean field approximation. We discussed the implication of changes in coupling constant of the delta baryonic resonance on the observable of the neutron star. A detailed analysis of the equation of state and of the baryonic effective mass in respect to changes in the delta coupling constants is carried out. We focus attention on a new aspect observed for pressure when varying the baryonic density of the medium; a first order phase transition like a liquid-gas phase transition was observed for an acceptable range of delta coupled constant values. We have explored the implication of this aspect for the neutron star structure and their maximum masses.

In this paper, we discuss the impact of rotation on the particle composition of rotating neutron stars (pulsars). Particular emphasis is put on the formation of quark matter during stellar spin-down, driven by continuous gravitational compression. Our study is based on modern models for the nuclear equation of state whose parameters are tightly constrained by nuclear data, neutron star masses, and the latest estimates of neutron star radii.

Stars known as pulsars are generally modeled as magnetized spheres made of neutrons with high rotation frequency. It is known that such stars are spinning down and this braking is measured by a parameter, n, known as braking index. For the canonical model such parameter should have a single value for all pulsars: n = 3. However, from observations it is known that n diverges from 3. In this work, differently from the canonical model, we have hypothesized the existence of a variation of the moment of inertia of the star through a time-varying radius. Using energy conservation we find the values for the variation of the radius of our pulsar sample. Our results indicate that it may be reasonable to consider that the radius of pulsars can be changing with time.

The theoretical calculation of braking indices of pulsars is still an open problem. In this work we present a study on this issue which adapts the model that assumes that pulsars are rotating magnetic dipoles by introducing a compensating component in the energy conservation equation of the system. Such component relates to an effective force that varies with the first power of the tangential velocity of the pulsar’s crust. We tested the proposed model using data available.

The goal of this work is to apply Bayesian statistics to the problem of pulsars in order to compute the Bayes factor and investigate which one among different EoS could better fit known pulsar data, regarding the rate of decrease of the angular velocity versus the angular velocity itself. We also find the posterior distribution and the best fit for some relevant parameters of the pulsar like the mass and the magnetic field.

We study the QCD phase diagram using a non-local SU(3) NJL model with vector interactions among quarks. We analyze several thermodynamic quantities such as entropy and specific heat, and study the influence of vector interactions on the thermodynamic properties of quark matter. Upon imposing electric charge neutrality and baryon number conservation on the field equations, we compute models for the equation of state of the inner cores of proto-neutron stars by providing a non-local treatment of quark matter for astrophysics.

The SN1987A in the Giant Magellanic Cloud was an amazing and extraordinary event because it was detected in real time for different neutrinos experiments ($\nu$s) around the world. Approximate $\sim 25$ events were observed in three different experiments: Kamiokande II (KII) $\sim 12$, Irvine-Michigan-Brookhaven (IMB) $\sim 8$ e Baksan $\sim 5$, plus a contrived burst at Mont Blanc (Liquid Scintillator Detector - LSD) later dismissed because of energetic requirements (Aglietta et al. 1988). The neutrinos have an important play role into the neutron star newborn: at the moment when the supernova explodes the compact object remnant is freezing by neutrinos ($\sim 99\%$ energy is lost in the few seconds of the explosion). The work is motivated by neutrinos’ event in relation arrival times where there is a temporal gap between set of events ($\sim 6\text{s}$). The first part of dataset came from the ordinary mechanism of freezing and the second part suggests different mechanism of neutrinos production. We tested two models of cooling for neutrinos from SN1987A: 1st an exponential cooling is an ordinary model of cooling and 2nd a two-step temperature model that it considers two bursts separated with temporal gap. Our analysis was done with Bayesian tools (Bayesian Information Criterion - BIC) The result showed strong evidence in favor of a two-step model against one single exponential cooling ($ln{\text{B}}_{ij}>5.0$), and suggests the existence of two neutrino bursts at the moment the neutron star was born.

We study the possibility of a hadron-quark phase transition in the interior of neutron stars, taking into account different schematic evolutionary stages at finite temperature. Furthermore, we analyze the astrophysical properties of hot and cold hybrid stars, considering the constraint on maximum mass given by the pulsars J1614-2230 and J1614-2230. We obtain cold hybrid stars with maximum masses $\ge 2$ M${}_{\odot }$. Our study also suggest that during the proto-hybrid star evolution a late phase transition between hadronic matter and quark matter could occur, in contrast with previous studies of proto-neutron stars.

The possible existence of deconfined matter in the cores of neutron stars has been studied for over three decades without a firm indication either for or against this proposition. Analysis mostly rely on the comparison of mass-radius curves obtained for different compositions with observational data on the mass of the most massive objects of this kind accurately determined. Nevertheless, there are other possibilities for indirectly studying the internal composition of this class of compact objects, e.g, analyzing cooling behavior, X-ray bursts, supernova’s neutrinos. We present calculations on the expected nucleosynthesis spectra for the strange star-strange star merger scenario as means to test the strange quark matter hypothesis and its realization inside such objects. This would result very different from the typical r-process nucleosynthesis expected in neutron star mergers since the high temperature deconfinement of strange matter would produce large amounts of neutrons and protons and the mass buildup would proceed in a Big-Bang nucleosynthesis like scenario. The neutron to proton ratio would allow to reach the iron peak only, a very different prediction from the standard scenario. The resultant light curve indicate it may be compatible with that of a kilonova depending on the specific details of the ejecta.

Considering LQCD results for the quark condensates we determine the thermomagnetic dependence of NJL model coupling and then study the thermodynamical properties of hot magnetized quark matter.

In this work we study the chiral transition in quark matter at finite temperature and in the presence of a chiral imbalance in the Nambu–Jona-Lasinio model. We use the Medium Separation Scheme (MSS) to rewrite divergent momentum integrals that appear in the model in such way that we can conciliate results obtained with the model and recent lattice results for the chiral transition.

Under the action of field intensities around the Schwinger critical field, a dense electron gas behaves as unidimensional, exerting strong pressure along the applied field. We suggest a model for maintaining the magnetic field self-consistently, by assuming spin parallel pairing leading to a partial bosonization of the electron gas, which is described by a charged vector boson field, able to experience condensation, leading to a ferromagnetic behavior. Our aim is to suggest a possible quantum relativistic self-magnetized jet model. High frequency photons will be deviated also along paths parallel to the external field, leading to a model for a jet. Any addition of matter and/or energy to the electron system, would contribute to increase the kinetic energy along the magnetic field axis, an the jet may extend for long distances.

We study the Quantum Faraday rotation starting from the photon self-energy in the presence of a constant magnetic field. The Faraday angle is calculated in the non-degenerate regime and for weak field limit. Two physical scenarios, possibly characterized by these conditions, are the recombination epoch and the jets originated in pulsars. We discuss the resonant behavior that the Faraday angle exhibits in these scenarios and investigate the possibility of detecting cosmic magnetic fields through this resonant mechanism.

We study the equation of motion of neutral vector bosons bearing a magnetic moment (MM). The effective rest mass of vector bosons is a decreasing function of the magnetic field intensity. Consequently a diffuse condensation of the bosons appears below a critical value of the field. For typical values of densities and magnetic fields the magnetization is positive and the neutral boson system can maintain a magnetic field self-consistently. A discussion of the relevance in astrophysics is presented.

We consider the analytical Bonnor solution for a relativistic neutron star and discuss about the limit in which this solution satisfies Einstein-Maxwell equations. We study the gravitational redshift for Bonnor solution without electric charge. We find that for stars with magnetic fields up to $10^{16}\mathrm{\text{G}}$ in the center, the gravitational redshift for Bonnor metric differs from the Schwarzschild solution on a term that depends on magnetic dipole moment and the polar angle of the emission signal.

The aim of the present work is to try to find an equation of state (EoS) directly from the solution of the Tolman-Oppenheimer-Volkoff (TOV) equations subject to known observational constraints to the maximum mass and corresponding radius and baryonic mass. Hence, instead of solving the TOV equations with an EoS that enters as input, we obtain an EoS as output.

Neutron stars manifest themselves as different classes of astrophysical sources that are associated to distinct phenomenology. Here we focus our attention on magnetars (or strongly magnetized neutron stars) that are associated to Soft Gamma Repeaters and Anomalous X-ray Pulsars. The magnetic field on surface of these objects, reaches values greater than $10^{15}$ G. Under intense magnetic fields, relativistic effects begin to be decisive for the definition of the structure and evolution of these objects. We are tempted to question ourselves to how strengths fields affect the structure of neutron star. In this work, our objective is study and compare two solutions of Einstein-Maxwell equations: the Bonnor solution, which is an analytical solution that describe the exterior spacetime for a massive compact object which has a magnetic field that is characterize as a dipole field and a complete solution that describe the interior and exterior spacetime for the same source found by numerical methods). For this, we describe the geodesic equations generated by such solutions. Our results show that the orbits generated by the Bonnor solution are the same as described by numerical solution. Also, show that the inclusion of magnetic fields with values up to $10^{17}$G in the center of the star does not modify sharply the particle orbits described around this star, so the use of Schwarzschild solution for the description of these orbits is a reasonable approximation.

In this work I present numerical magnetohydrodynamic (MHD) simulations of the early dynamics around newly born neutrons stars using the AMR Flash method. When the core-collapse supernovae occurs a reverse shock is formed allowing strong accretion onto the neutron star surface (hypercritical phase). In such regime large amounts of matter are deposited on the neutron star surface, submerging the magnetic field in the new crust. When the hypercritical regime is over, the magnetic field can suffer a reemergence episode due to magnetic diffusion processes, allowing the delayed switch-on of pulsars.

In 1918, Joseph Lense and Hans Thirring discovered the gravitomagnetic (GM) effect of Einstein field equations in weak field and slow motion approximation. They showed that Einstein equations in this approximation can be written as in the same form as Maxwell’s equation for electromagnetism. In these equations the charge and electric current are replaced by the mass density and the mass current. Thus, the gravitomagnetism formalism in astrophysical system is used with the mass assuming the role of the charge. In this work, we present the deduction of gravitoelectromagnetic equations and the analogue of the Lorentz force in the gravitomagnetism. We also discuss the problem of Mercury’s perihelion advance orbit, we propose solutions using GM formalism using a dipole-dipole potential for the Sun-Planet interaction.

We perform a pure quantum-mechanical calculation for the non-reactive scattering in atomic and molecular hydrogen-hydrogen collisions, i.e. H₂+H₂ and H+H₂. Different potential energy surfaces (PESs) for the H₃ and H₄ atomic systems have been used. The rigid rotor model of the diatomic molecules, i.e. when the distance between hydrogen atoms is fixed at some average equilibrium value, has been applied in our calculation. After this preparatory stage the astrophysical H₂-cooling function can be estimated at different astrophysical conditions and temperatures.

In many studies of meson-baryon interactions with short one gluon exchange potential (OGEP), usually a full non-relativistic reduction, at the quark level Hamiltonian, is performed. In systems like ${\eta }_{c}N$, light and heavy quarks are present, which in principle would require only a partial non-relativistic reduction. We shal start from a JKJ relativistic quark Hamiltonian and apply a partial non-relativistic reduction in order to obtain a OGEP between heavy and light quarks (heavy-light quark potential).

The problem of a relativistic bound-state system consisting of two scalar bosons interacting through the exchange of another scalar boson, in 2+1 space-time dimensions, has been studied. The Bethe-Salpeter equation (BSE) was solved by adopting the Nakanishi integral representation (NIR) and the Light-Front projection. The NIR allows us to solve the BSE in Minkowski space, which is a big and important challenge, since most of non-perturbative calculations are done in Euclidean space, e.g. Lattice and Schwinger-Dyson calculations. We have in this work adopted an interaction kernel containing the ladder and cross-ladder exchanges. In order to check that the NIR is also a good representation in 2+1, the coupling constants and Wick-rotated amplitudes have been computed and compared with calculations performed in Euclidean space. Very good agreement between the calculations performed in the Minkowski and Euclidean spaces has been found. This is an important consistence test that allows Minkowski calculations with the Nakanishi representation in 2+1 dimensions. This relativistic approach will allow us to perform applications in condensed matter problems in a near future.

We study the QCD phase diagram in the framework of a nonlocal three-flavor quark model. We determine the model parameters from vacuum meson phenomenology, considering lattice QCD-inspired nonlocal form factors. Then we analyze the features of the deconfinement and chiral restoration transitions for systems at nonzero temperature and chemical potential.

We presented the exclusive photoproduction of Upsilon(1S,2S,3S) in pp and pA reactions at the LHC energies for Ultra Peripheral Collisions(UPC). It was calculated in the dipole formalism, with the dipoles models: GBW, CGC and b-CGC. The dipole formalism is characterised by a saturation effect, e.g, the mimic gluon distribution becomes saturated at low-x. This approach has shown a good agreement with the experimental data since HERA and with recent data released by LHCb for processes involving $\mathrm{\Psi }(1S,2S)$, $\mathrm{{\rm Y}}(1S)$, $\rho$ for UPC in pp.

The exclusive photoproduction of the heavy vector mesons $\mathrm{\Psi }(1S,2S)$ is investigated in the context of ultra-peripheral collisions proton-proton and nucleus-nucleus for the energies available at the LHC run 2. Using the light-cone color dipole formalism, it was calculated the transverse momentum distribution in the central rapidity region, in which it is expected major contribution for the process.

We analyse the hadron/quark phase transition described by the Nambu-Jona-Lasinio (NJL) model [quark phase] and the extended Nambu-Jona-Lasinio model (eNJL) [hadron phase]. While the original formulation of the NJL model is not capable of describing hadronic properties due to its lack of confinement, it can be extended with a scalar-vector interaction so it exhibits this property, the so-called eNJL model. As part of this analysis, we obtain the equations of state within the SU(2) versions of both models for the hadron and the quark phases and determine the binodal surface.

Within the framework of cold magnetized SU(2) Nambu-Jona-Lasinio model we evaluate the ${\pi }_0$ and $\sigma$ pole mass, as well as, $f_{{\pi }_0}$, $g_{{\pi }_{0}qq}$ at zero baryon density. We employ a magnetic field dependent coupling, $G(eB)$, fitted to reproduce lattice QCD results for the quark condensates. In particular, we find that the ${\pi }_0$ meson mass systematically decreases when the magnetic field increases, in good agreement with recent lattice calculations.

We investigate the rapidity and transverse momentum distributions of the prompt photon production at the LHC energies considering the color dipole approach. We compare the predictions from distinct models for the dipole cross section, where parton saturation models at high energies are expected to be important at the forward rapidities in $pp$ and $pA$ collisions at the LHC.

In this contribution we provide predictions for total, elastic and single diffractive cross sections calculated for the proton-proton collisions at the LHC in centre-of-mass energies of 0.9, 7, 8 and 14 TeV. We consider the framework of the Miettinen-Pumplin model which correctly describes the lower energy data available by Fermilab-Tevatron. Our predictions are based on the fitted parameters of the model for the Tevatron measurements and for TOTEM-LHC measurements at 7 TeV. We extrapolate the results for the higher energies runs of LHC and provide predictions for them. We verify that those prediction are in agreement with the recent CERN-ATLAS Collaboration result.

In the present work, we investigated the exclusive diffractive production of charmonium in pronton-nucleus collisions at the Large Hadron Collider (LHC) energies. Such exclusive production reactions possess a cleaner experimental signal than inclusive production once it is characterized by low multiplicity of particles between final produced state and the incident protons of collider beam. The considered theoretical framework was the perturbative model of Quantum Cromodynamics (QCD) for the Pomeron exchange. In particular, we have used the resolved Pomeron model which depends on the Pomeron flux and Pomeron parton distribution functions. The main goal is to provide predictions for the single diffractive cross section for the J/Psi meson production at the energies of 5.02 TeV and 8.8 TeV. We have shown that a measurement is feasible as the order of magnitude is 400 microbarns even absorption corrections. Furthermore, we analyze the ratio of the diffractive to inclusive cross section which allows theoretical uncertainties to be canceled, mostly those associated to approximations performed in inclusive case.

At high energies the Pomeron plays a crucial part in describing the soft interactions. In the light of LHC (Large Hadron Collider) data we perform a detailed analysis of proton-proton ($pp$) and antiproton-proton ($\bar{p}p$) forward scattering data in order to determine the intercept and the slope of the soft Pomeron trajectory. This analysis is performed based on Regge theory using Born-level amplitudes. We investigate the role of the proton-Pomeron vertex form and of the nearest $t$-channel singularity. We give predictions for the total cross section and the ratio of the real part to the imaginary part of the elastic amplitude in $pp$ collisions at LHC and cosmic-ray energies.

The high gluon density in the initial state of hadronic collisions at LHC energies implies that the probability of multiple parton interactions within one proton-proton collision increases. In particular, this motivates one to investigate the importance of Double Parton Scattering (DPS) processes at the LHC. In a DPS process one can have, from one proton-proton collision, two interacting partons coming from each colliding hadron. In this context, the relation between the double parton distribution functions (dPDF) and the usual parton distribution functions (PDF) is discussed, and some formulae for the DPS cross section are compared. Our results focus on the production of different final states related to two heavy quark-antiquark pairs. Those include $c\bar{c}c\bar{c}$, which is called the golden channel of DPS, $b\bar{b}b\bar{b}$ and $c\bar{c}b\bar{b}$.

We study the BEC-BCS crossover in the presence of an external magnetic field for a two color NJL model with diquark interactions, giving special attention to the regularization scheme. We found a inverse magnetic catalysis on the critical chemical potentials, both for BEC phase transition and the BEC-BCS crossover for small values of magnetic fields, and a magnetic catalysis for large $eB$.

The Fock-Tani formalism is a first principle method to obtain effective interactions from microscopic Hamiltonian. Originally derived for meson-meson or baryon-baryon scattering, we present the corresponding equations for meson-baryon scattering. In particular we shall obtain the low energy cross sections for the $K^{-}+p\to \mathrm{\Lambda }+\eta$ channel.

In the last years many exotic states have been identified in several colliders around the world. One of the exotic states provided in QCD is the glueball. Using a non-relativistic gluon bound-state model, we compute $\mathrm{\Gamma }(G\to \gamma \gamma )$, where $G$ is a pseudoscalar, tensor, or scalar digluon. For the starting from the amplitudes we considers the process $\gamma \gamma \to g^{\ast }{g}^{\ast }$ at threshold, where the amplitudes are obtained in perturbative QCD at lowest order by deriving them from QED calculation and the $g^{\ast }$s are massive constituent gluons. In this calculation the unknown parameters of the model, such as the digluon wave function, are obtained using measured values of $\mathrm{\Gamma }(J/\mathrm{\Psi }\to G\gamma )$. Our theorical results are compared with the present experimental limits for the various glueballs candidates.

With the development of experiments in particle accelerators, there have been many new particles discovered. Some of these new particles are called exotic particles and are predicted by Quantum Chromodynamics (QCD). There are various models for the study of these particles, and a possible way to study the exotic particle production is through the study of meson production in two-photon interactions at high-energy collisions due his clean experimental signal. In this contribution, we calculate the meson production in two-photon interactions at LHC energies considering proton-proton collisions to estimate the total cross section for the production of exotic states.

The Fock-Tani representation is a field theory formalism appropriated for the simultaneous treatment of composite particles and their constituents. The 3P0 model is a typical decay model which considers only OZI-allowed strong decays. The model considers a quark-antiquark pair created with the vacuum quantum numbers in the presence of the initial state meson. It is described as the non-relativistic limit of the pair creation Hamiltonian. Applying the Fock-Tani transformation to the microscopic Hamiltonian of the pair creation produces the characteristic expansion in powers of the wavefunction, where the 3P0 model is the lowest order in the expansion. The corrected 3P0 model (C3P0) is obtained from higher orders in the expansion, by the introduction of the bound state kernel $\mathrm{\Delta }$, called the bound state correction. The goal of this work is to study the application of the 3P0 model and C3P0 model in detail for the strange charmed meson sector ($D_{SJ}$ meson). In particular, we shall calculate the decay amplitudes and decay rates of the $D_{s1}{(2536)}^{+}$.

In this work we have obtained an effective Hamiltonian to describe the strong decay of pseudoscalar glueball, where the microscopic interaction between the constituent gluons have been taking into account. The pseudoscalar glueball candidate we have considered here is the $X(1835)$ resonance. In our calculation the $X(1835)$ was a pure glueball.

A form to describe hadron strong decays is in terms of quark and gluon degrees of freedom in microscopic decay models. Initially we assume that strong decays are driven by the same inter-quark Hamiltonian which determines the spectrum, and that it incorporates gaussian confinement. An $A\to BC$ decay matrix element of the JKJ Hamiltonian involves a pair-production current matrix elements times a scattering matrix element. Diagrammatically this corresponds to an interaction between an initial line and produced pair. In this work we apply the model to the light meson sector and calculate the decay rate, comparing with the experimental values.

We study hadronic weak decays using an approach which consists in a mapping technique, the Fock-Tani formalism, in order to obtain an effective weak Hamiltonian starting from a contact microscopic interaction. An additional effect is manifest in this formalism associated to the extended nature of mesons: bound-state corrections which can be related to CP violation parameters.

In this paper we study the anomalous movement of planet precession as compared with different observational data from Ephemerides of the Planets and the Moon (EPM2008 and EPM2011) and the Planetary and Lunar Ephemeris (INPOP10a). Using a heuristic methodology we obtain a very close results to observations.

Astrophysics and Space Science are becoming increasingly characterised by what is now known as “big data”, the bottlenecks for progress partly shifting from data acquisition to “data mining”. Truth is that the amount and rate of data accumulation in many fields already surpasses the local capabilities for its processing and exploitation, and the efficient conversion of scientific data into knowledge is everywhere a challenge. The result is that, to a large extent, isolated data archives risk being progressively likened to “data graveyards”, where the information stored is not reused for scientific work.

Responsible and efficient use of these large data-sets means democratising access and extracting the most science possible from it, which in turn signifies improving data accessibility and integration. Improving data processing capabilities is another important issue specific to researchers and computer scientists of each field. The project presented here wishes to exploit the enormous potential opened up by information technology at our age to advance a model for a science data center in astronomy which aims to expand data accessibility and integration to the largest possible extent and with the greatest efficiency for scientific and educational use. Greater access to data means more people producing and benefiting from information, whereas larger integration of related data from different origins means a greater research potential and increased scientific impact.

The project of the BSDC is preoccupied, primarily, with providing tools and solutions for the Brazilian astronomical community. It nevertheless capitalizes on extensive international experience, and is developed in full cooperation with the ASI Science Data Center (ASDC), from the Italian Space Agency, granting it an essential ingredient of internationalisation. The BSDC is Virtual Observatory-complient and part of the “Open Universe”, a global initiative built under the auspices of the United Nations.