arXiv subjects

Behrouz Mirza

Publications and source records attributed to Behrouz Mirza.

At least 37 records · Page 2Linked to original sources

arXiv2020

Relativistic Quantum Information of Anyons

In this paper, a method is developed to investigate the relativistic quantum information of anyons. Anyons are particles with intermediate statistics ranging between Bose-Einstein and Fermi-Dirac statistics, with a parameter $α$ ($0<α<1$) characteristic of this intermediate statistics. A density matrix is also introduced as a combination of the density matrices of bosons and fermions with a continuous parameter, $α$, that represents the behavior of anyons. This density matrix reduces to bosonic and fermionic density matrices in the limits $α\rightarrow 0$ and $α\rightarrow 1$,respectively. We compute entanglement entropy, negativity, and coherency for anyons in non-inertial frames as a function of $α$. We also computed quantum fisher information for these particles. Semions, which are particles with $α= 0.5$, were found to have minimum quantum fisher information with respect to $α$ than those with other values of fractional parameter.

quant-ph↗

arXiv2020

Late time dynamics of $f(R, T, R_{μν}T^{μν})$ gravity

Dynamical behavior and future singularities of $f(R, T,R_{μν}T^{μν})$ gravitational theory are investigated. This gravitational model is a more complete form of the $f(R,T)$ gravity which can offer new dynamics for the universe. We investigate this gravitational theory for the case $f = R + αR_{μν}T^{μν}$ using the method of autonomous dynamical systems and by assuming an interaction between matter and dark energy. The fixed points are identified and the results are consistent with standard cosmology and show that for small $α$, the radiation dominated era is an unstable fixed point of the theory and the universe will continue its procedure toward matter era which is a saddle point of the theory and allows the evolution to dark energy dominated universe. Finally the dark energy dominated epoch is a stable fixed point and will be the late time attractor for the universe. We also consider future singularities for the two $f = R + αR_{μν}T^{μν}$ and $f = R +αRR_{μν}T^{μν}$ cases and for $w = 0,\dfrac{1}{3},1$ and $-1$. Our results show that for the case of $f = R + αR_{μν}T^{μν}$, the future singularities of the universe will happen in the same condition as do for the Einstein-Hilbert FRW universe. However, a new type of singularity is obtained for $f = R +αRR_{μν}T^{μν}$ that is captured by $t\rightarrow t_s;\ a \rightarrow a_s;\ ρ\rightarrow \infty;$ and $\ |p| \rightarrow 0$.

gr-qc↗

arXiv2020

Generating odd-dimensional rotating black holes with equal angular momenta by using the Kerr-Schild Cartesian form of metric

The Newman-Janis (NJ) method is a prescription to derive the Kerr space-time from the Schwarzschild metric. The BTZ, Kerr and five-dimensional Myers-Perry (MP) black hole solutions have already been generated by different versions of the NJ method. However, it is not known how to generate the metric of higher-dimensional (d > 6) rotating black holes by this method. In this paper, we propose the simplest algorithm for generation of the five-dimensional MP metric with two arbitrary angular momenta by using the Kerr-Schild form of the metric and quaternions. Then, we present another new two-step version of the NJ approach without using quaternions that generate the five-dimensional MP metric with equal angular momenta. Finally, the extension of the later procedure is explained for the higher odd-dimensional rotating black holes (d > 5) with equal angular momenta.

gr-qc↗

arXiv2020

Maximum rate of entropy emission

It is shown that adding hair like electric charge or angular momentum to the black hole decreases the amount of entropy emission. This motivates us to study the emission rate of entropy from black holes and conjecture a maximum limit (upper bound) on the rate of local entropy emission ($\dot{S}$) for thermal systems in four dimensional space time and argue that this upper bound is $\dot{S}\simeq k_{B} \sqrt{\frac{c^5}{\hbar G}}$. Also by considering Rènyi entropy, it is shown that Bekenstein-Hawking entropy leads to a maximum limit for the rate of entropy emission. We also suggest an upper bound on the surface gravity of the black holes which is called Planck surface gravity. Finally we obtain a relation between maximum rate of entropy emission, Planck surface gravity and Planck temperature of black holes.

gr-qc↗

arXiv2020

Holographic entanglement first law for d + 1 dimensional rotating cylindrical black holes

We calculate the holographic entanglement entropy for the rotating cylindrical black holes in $d+1$ dimensions as perturbations over $AdS_{d+1}$. This is accomplished based on the first order variation of the area functional in arbitrary dimensions. For these types of black holes, the angular momentum appears at the first order of the perturbative expansion of the holographic entanglement entropy for spacetime dimensions of d +1 $\geq$ 4. We obtain a form of holographic entanglement first law in the presence of both energy and angular momentum.

gr-qc↗

arXiv2020

Dynamical behavior of the Universe: an entropic force scenario

Entropic force originates in the assumption that there is a horizon for the universe. This horizon gives rise to additional terms in the equations of motion. Using dynamical system calculations, our results show that in the presence of dark energy for certain conditions, the last attractor of this theory will be dark energy epoch, but in the absence of dark energy, entropic force energy portion will have the lead role in the late time universe and is responsible for accelerated expansion of that. Interestingly, assuming both entropic force terms and dark energy to have their share of energy density of the universe, we have found that, in certain conditions entropic force dominated epoch is a stable fixed point while the dark energy epoch is a saddle point.

gr-qc↗

arXiv2019

Geometrothermodynamics as a singular conformal thermodynamic geometry

In this letter, we first redefine our formalism of the thermodynamic geometry introduced in [1,2] by changing coordinates of the thermodynamic space by means of Jacobian matrices. We then show that the geometrothermodynamics (GTD) is conformally related to this new formalism of the thermodynamic geometry. This conformal transformation is singular at unphysical points were generated in GTD metric. Therefore, working with our metric neatly excludes all unphysical points without imposing any constraints.

gr-qc↗

arXiv2019

Holographic entanglement entropy for charged accelerating AdS black holes

We investigate the holographic entanglement entropy in the Rindler-AdS space-time to obtain an exact solution for the corresponding minimal surface. Moreover, the holographic entanglement entropy of the charged single accelerated AdS Black holes in four dimensions is investigated. We obtain the volume of the codimension one-time slice in the bulk geometry enclosed by the minimal surface for both the RindlerAdS space-time and the charged accelerated AdS Black holes in the bulk. It is shown that the holographic entanglement entropy and the volume enclosed by the minimal hyper-surface in both the Rindler spacetime and the charged single accelerated AdS Black holes (C-metric) in the bulk decrease with increasing acceleration parameter. Behavior of the entanglement entropy, subregion size and value of the acceleration parameter are investigated. It is shown that for jAj < 0:2 a larger subregion on the boundary is equivalent to less information about the space-time.

hep-th↗

arXiv2019

Topological invariants of the Ryu-Takayanagi ($RT$) surface used to observe holographic superconductor phase transition

We study the phase transitions in the metal/superconductor system using topological invariants of the Ryu-Takayanagi ($RT$) surface and the volume enclosed by the $RT$ surface in the Lifshitz black hole background. It is shown that these topological invariant quantities identify not only the phase transition but also its order. According to these findings a discontinuity slope is observed at the critical points for these invariant quantities that correspond to the second order of phase transition. These topological invariants provide a clearer illustration of the superconductor phase transition than do the holographic entanglement entropy and the holographic complexity. Also, the backreaction parameter, $k$, is found to have an important role in distinguishing the critical points. The reducing values of the parameter $k$ means that the backreaction of the matter fields are negligible. A continuous slope is observed around the critical points which is characteristic of the probe limit. In addition, exploring the nonlinear electrodynamic, the effects of the nonlinear parameter, $β$, is investigated. Finally the properties of conductivity are numerically explored in our model.

hep-th↗

arXiv2019

Electromagnetic self-force in the five dimensional Myers-Perry space time

We calculate the effects of the electromagnetic self-force on a charged particle outside a five dimensional Myers-Perry space-time. Based on our earlier work [1], we obtain the self-force using quaternions in Janis-Newman and Giampieri algorithms. In four dimensional rotating space-time the electromagnetic self-force is repulsive at any point, however, in five dimensional rotational space-time, we find a point r0 where the electromagnetic self-force vanishes. For r < r0 (r > r0) the electromagnetic self-force is attractive (repulsive).

gr-qc↗

arXiv2018

Anyon Black Holes

We propose a correspondence between an Anyon Van der Waals fluid and a (2+1) dimensional AdS black hole. Anyons are particles with intermediate statistics that interpolates between a Fermi-Dirac statistics and a Bose-Einstein one. A parameter $α$ ($0<α<1$) characterizes this intermediate statistics of Anyons. The equation of state for the Anyon Van der Waals fluid shows that it has a quasi Fermi-Dirac statistics for $α> α_c$, but a quasi Bose-Einstein statistics for $α< α_c$. By defining a general form of the metric for the (2+1) dimensional AdS black hole and considering the temperature of the black hole to be equal with that of the Anyon Van der Waals fluid, we construct the exact form of the metric for a (2+1) dimensional AdS black hole. The thermodynamic properties of this black hole is consistent with those of the Anyon Van der Waals fluid. For $α< α_c$, the solution exhibits a quasi Bose-Einstein statistics. For $α> α_c$ and a range of values of the cosmological constant, there is, however, no event horizon so there is no black hole solution. Thus, for these values of cosmological constants, the AdS Anyon Van der Waals black holes have only quasi Bose-Einstein statistics.

hep-th↗

arXiv2018

Generating five-dimensional Myers-Perry black hole solution using quaternions

The Newman-Janis and Giampieri algorithms are two simple methods to generate stationary rotating black hole solutions in four dimensions. In this paper, we obtain the Mayers-Perry black hole from the Schwartzchild solution in five dimensions using quaternions. Our method generates the Mayers-Perry black hole solution with two angular momenta in one fell swoop.

gr-qc↗

arXiv2017

Mimetic f(T) Teleparallel gravity and cosmology

We formulate mimetic theory in f(T) teleparallel gravity where T is torsion scalar. It is shown that the construction of the mimetic theory in the teleparallel gravity requires the vierbeins to be left unchanged and the confomal transformation performed on the Minkowski metric of the tangent space. It is further argued that the conformal degree of freedom in this teleparallel mimetic theory becomes dynamical and mimics the behavior of cold dark matter. We also show that it is possible to employ the Lagrange multipliers method to formulate the mimetic theory in an f(T) theory without any auxiliary metric. The mimetic f(T) theory is examined by the method of dynamical system and it is found that there are five fixed points representing inflation, radiation, matter, mimetic dark matter and dark energy dominated eras in the theory if some conditions are satisfied. We examined the power-law model and its phase trajectories with these conditions.

gr-qc↗

arXiv2017

Constraining f(T) gravity by dynamical system analysis

We investigate the cosmological solutions of the $f(T)$ gravity theory using the method of dynamical systems. For this purpose a general form of the $f(T)$ function is considered and four conditions are defined that they have to satisfy in order to describe the standard cosmological history. We examine the power law, and another form of $f(T)$ against these conditions. For a power law function $f(T)= B(-T)^β$, $β$ must be less than one and unequal to $\frac{1}{2}$ to obtain a consistent cosmological model. We also investigate a model of inflation in this theory.

gr-qc↗

arXiv2017

Black holes with toroidal horizons in (d +1)-dimensional space-time

We investigate black holes with toroidal horizons in (d +1)-dimensional space-time. Using the solution phase space method, we calculated conserved charges for these black holes before exploring some features of this metric including its entropy and thermodynamic quantities. Another aspect of the study involves obtaining a general exact static interior solution for uncharged black holes with toroidal horizons in (d+1)-dimensional space-time. Finally, an interior solution for charged black holes is obtained.

gr-qc↗

arXiv2017

Lorentz Gauge Theory of Gravity in Electron Positron Colliders

Lorentz gauge theory (LGT) is a feasible candidate for theory of quantum gravity in which routine field theory calculations can be carried out perturbatively without encountering too many divergences. In LGT spin of matter also gravitates. The spin-generated gravity is expected to be extremely stronger than that generated by mass and could be explored in current colliders. In this article the observable signals of the theory in an electron-positron collider is investigated. We specifically study pair annihilation into two gravitons, and LGT corrections to processes like $e^-+e^+\rightarrow μ^-+μ^+$ and $e^-+e^+\rightarrow e^-+e^+$.

gr-qc↗

arXiv2017

Exponential nonlinear electrodynamics and backreaction effects on Holographic superconductor in the Lifshitz black hole background

We analytically describe the properties of the s-wave holographic superconductor with the Exponential nonlinear electrodynamics in the Lifshitz black hole background in four-dimensions. Employing an assumption the scalar and gauge fields backreact on the background geometry, we calculate the critical temperature as well as the condensation operator. Based on Sturm-Liouville method, we show that the critical temperature decreases with increasing exponential nonlinear electrodynamics and Lifshitz dynamical exponent, z, indicating that condensation becomes difficult. Also we find that the effects of backreaction has a more important role on the critical temperature and condensation operator in small values of Lifshitz dynamical exponent, while z is around one. In addition, the properties of the upper critical magnetic field in Lifshitz black hole background using Sturm-Liouville approach is investigated to describe the phase diagram of the corresponding holographic superconductor in the prob limit. We observe that the critical magnetic field decreases with increasing Lifshitz dynamical exponent, z, and it goes to zero at critical temperature, independent of the Lifshitz dynamical exponent, z.

hep-th↗

arXiv2017

A Homogeneous and Isotropic Universe in Lorentz Gauge Theory of Gravity

Lorentz gauge theory of gravity was recently introduced. We study the homogeneous and isotropic universe of this theory. It is shown that some time after the matter in the universe is diluted enough, at $z \sim 0.6$, the decelerating expansion shifts spontaneously to an accelerating one without a dark energy. We discuss that Lorentz gauge theory puts no constraint on the total energy content of the universe at present time and therefore the magnitude of vacuum energy predicted by field theory is not contradictory anymore. It is demonstrated that in this theory the limit on the number of relativistic particles in the universe is much looser than in GR. An inflationary mechanism is discussed as well. We show that the theory, unlike GR, does not require the slow-roll or similar conditions to drive the inflation at the beginning of the universe.

gr-qc↗