arXiv subjects
Publications and source records attributed to B. Pourhassan.
In this paper we construct rotating charged hairy black hole in (2+1) dimensions for infinitesimal black hole charge and rotation parameters. Then we consider this black hole as particle accelerator and calculate the center-of-mass energy of two colliding test particles near the rotating charged hairy black hole in (2+1) dimensions. As we expected, the center-of-mass energy has infinite value.
In this paper, we consider the charged non-extremal black hole at five dimensional N = 2 supergravity. We study thermodynamics of AdS_{5} black hole with three equal charges (q_{1} = q_{2} = q_{3} = q). We obtain Schrodinger like equation and discuss the effective potential. Then, we consider the case of the perturbed dilaton field background and find presence of odd coefficients of the wave function. Also we find that the higher derivative corrections have no effect on the first and second even coefficients of the wave function.
In this paper we consider holographic dark energy model with corrected holographic energy density and show that this model may be equivalent to the modified Chaplygin gas model. Then we obtain relation between entropy corrected holographic dark energy model and scalar field models. We do these works by using choices of IR cut-off length proportional to the Hubble radius, the event horizon radius, the Ricci length, and the Granda-Oliveros length.
In this paper, viscous generalized Chaplygin gas as a model of dark energy considered. We assume non-constant bulk viscous coefficient and study dark energy density. We consider several cases of density-dependent viscosities. We find that, in the special case, the viscous generalized Chaplygin gas is corresponding to modified Chaplygin gas.
In this work, we follow Kim and Yamada (JHEP1107 (2011) 120) and utilize AdS in light-cone frame to derive thermodynamic and transport properties of two kinds of Schrödinger black holes with hyperscaling violation. In that case, we show entropy and temperature are depend on $θ$. In $θ=0$ we see our results are agree with the work of Kim and Yamada. We also construct R-charged black hole with hyperscaling violation and obtain thermodynamics and transport properties.
In this paper we consider the problem of a moving heavy quark through a hot non-relativistic, non-commutative Yang-Mills plasma. We discuss about the configuration of the static quark and obtain the quasi-normal modes. Also we find the diffusion constant for the moving heavy quark. The main goal of this study is calculating the jet-quenching parameter for the non-relativistic, non-commutative theory and comparing it with drag forces which recently obtained from the another independent work [1]
In this paper we study the ratio of shear viscosity to entropy, electrical and thermal conductivities for the R-charged black hole in STU model. We generalize previous works to the case of a black hole with three different charges. Actually we use diffusion constant to obtain ratio of shear viscosity to entropy. By applying the thermodynamical stability we recover previous results. Also we investigate the effect of higher derivative corrections.
In this paper we calculate the center-of-mass energy of two colliding test particles near the rotating and non-rotating Horava-Lifshitz black hole. For the case of slowly rotating KS solution of Horava-Lifshitz black hole we compare our results with the case of Kerr black holes. We confirm the limited value of the center-of-mass energy for the static black holes and unlimited value of the center-of-mass energy for the rotating black holes. Numerically, we discuss temperature dependence of the center-of-mass energy on the black hole horizon. We obtain the critical angular momentum of particles. In this limit the center-of-mass energy of two colliding particles in the neighborhood of the rotating Horava-Lifshitz black hole could be arbitrarily high. We found appropriate conditions where the critical angular momentum could have an orbit outside the horizon. Finally, we obtain center-of-mass energy corresponding to this circle orbit.
In this paper, we study the equation of circular loops with time-dependant tension in the BTZ black hole background. We obtain various cases where cosmic string loops finally collapse to form black holes. Also, we study effect of the BTZ black hole mass and angular momentum on the evolution of cosmic string loops. We find the critical values of initial radii as a limit for the cosmic string loops collapsing to form black holes.
In this paper, we investigate thermal equilibrium in string gas cosmology which is dominated by closed string.We consider two interesting regimes, Hagedorn and radiation regimes.We find that for short strings in small radius of Hagedorn regime very large amount of energy requested to have thermal equilibrium but for long strings in such system a few energy is sufficient to have thermal equilibrium. On the other hand in the large radius of Hagedorn regime, which pressure is not negligible, we obtain a relation between the energy and pressure in terms of cosmic time which is satisfied by thermal equilibrium. Then we discuss about radiation regime and find that in all cases there is thermal equilibrium.
In this paper we use the AdS/CFT correspondence to compute the jet-quenching parameter in a N=2 thermal plasma. We consider the general three-charge black hole and discuss some special cases. We add a constant electric field to the background and find the effect of the electric field on the jet-quenching parameter. Also we include higher derivative terms and obtain the first-order correction for the jet-quenching parameter.
In this paper, we consider a rotating heavy quark-antiquark ($q\bar{q}$) pair in a ${\mathcal{N}}$=4 SYM thermal plasma. We assume that $q\bar{q}$ center of mass moves at the speed $v$ and furthermore they rotate around the center of mass. We use the AdS/CFT correspondence and consider the effect of external electromagnetic field on the motion of the rotating meson. Then we calculate the jet-quenching parameter corresponding to the rotating meson in the constant electric field.
In this paper we consider the drag force problem in the STU model. Already this problem and related topics were studied in ${\mathcal N}=4$ SYM theory. Here we study the same problem in ${\mathcal N}=2$ supergravity theory with an R-charge black hole (the STU model). This paper extends our previous work [1,2] by studying more general charge configurations and by taking into account the effect of a constant electromagnetic field and higher derivative corrections. We consider a single quark and a $q \bar q$ pair in a three charge non-extremal black hole background. First by using the AdS/CFT correspondence, we obtain the drag force, the diffusion coefficient, the total energy and momentum, quasinormal modes, and the effect of higher derivative corrections for the single quark. Next we calculate the drag force for a $q \bar q$ pair which rotates around its center of mass. For the first time we study the motion of a rotating $q \bar q$ pair in ${\mathcal N}=2$ supergravity theory. We show that our results in the near-extremal limit agree with the energy loss of the moving quark which was calculated in the ${\mathcal N}=4$ SYM plasma.
The aim of this paper is to use correspondence between solutions in the $c=1$ matrix model collective field theory and coupled dilaton-gravity to a massless scalar field. First, we obtain the incoming and outgoing fluctuations for the time-dependent backgrounds with the lightlike and spacelike boundaries. In the case of spacelike boundaries, we have done here for the first time. Then by using the leg-pole transformations we find corresponding tachyon field in two dimensional string theory for lightlikes and spacelikes boundary.
In this paper we consider a quark moving in D=5, ${\mathcal{N}}=2$ supergravity thermal plasma. By using three charge non-extremal black hole solution (STU solution) we calculate drag force on the quark and diffusion constant from $AdS$/CFT correspondence.
In this paper we consider a moving quark in the thermal plasma at the N=2 Supergravity theory. By using the AdS/CFT correspondence we obtain energy loss of the quark. Then we consider the higher derivative corrections in charged AdS-black hole and calculate the drag force of the moving quark in the thermal plasma. Also we find a limit which N=2 Supergravity solutions are correspondening to the N=4 Super Yang-Mills solutions for the heavy quark.
In this paper we apply the entropy function formalism to the two-dimensional black hole which come from the compactification of the heterotic string theory with the dilaton coupling function. We find the Bekenstein-Hawking entropy from the value of the entropy function at its saddle point. Also we consider higher derivative terms. After that we apply the entropy function formalism to the Jackiw-Teitelboim (JT) model where we consider the effect of string-loop to this model.