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Roychowdhury D.,Sn Bose National Center For Basic Science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

Based on an analytic scheme and neglecting the back reaction effect several crucial properties of holographic s-wave superconductors have been investigated in the presence of an external magnetic field in the background of a D-dimensional Schwarzschild AdS space-time. Inspired by low energy limit of heterotic string theory, in the present Letter we replace the conventional Maxwell action by a Power Maxwell action. Immersing the holographic superconductors in an external static magnetic field the spatially dependent condensate solutions have been obtained analytically. Interestingly enough it is observed that condensation can form only below a certain critical field strength (Bc). Finally, and most importantly it is observed that the value of this critical field strength increases as the mass of the scalar particles gets higher, which indicates the onset of a harder condensation. © 2012 Elsevier B.V. Source


Lala A.,Sn Bose National Center For Basic Science
Advances in High Energy Physics | Year: 2013

In this paper, we have studied the critical phenomena in higher curvature charged AdS black holes. We have considered Lovelock-Born-Infeld-AdS black hole as an example. The thermodynamics of the black hole have been studied which reveals the onset of a higher-order phase transition in the black hole in the canonical ensemble (fixed charge ensemble) framework. We have analytically derived the critical exponents associated with these thermodynamic quantities. We find that our results fit well with the thermodynamic scaling laws and consistent with the mean field theory approximation. The suggestive values of the other two critical exponents associated with the correlation function and correlation length on the critical surface have been derived. © 2013 Arindam Lala. Source


Majhi B.R.,Sn Bose National Center For Basic Science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010

Hawking radiation from the black hole in Hořava-Lifshitz gravity is discussed by a reformulation of the tunneling method given in Banerjee and Majhi (2009) [17]. Using a density matrix technique the radiation spectrum is derived which is identical to that of a perfect black body. The temperature obtained here is proportional to the surface gravity of the black hole as occurs in usual Einstein gravity. The entropy is also derived by using the first law of black hole thermodynamics. Finally, the spectrum of entropy/area is obtained. The latter result is also discussed from the viewpoint of quasi-normal modes. Both methods lead to an equispaced entropy spectrum, although the value of the spacing is not the same. On the other hand, since the entropy is not proportional to the horizon area of the black hole, the area spectrum is not equidistant, a finding which also holds for the Einstein-Gauss-Bonnet theory. © 2010 Elsevier B.V. All rights reserved. Source


Ghosh S.,Sn Bose National Center For Basic Science
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

Within the framework of adiabatic regularization, we present a simple formalism to calculate number density and renormalized energy-momentum density of spin 1/2 particles in spatially flat FLRW spacetimes using an appropriate WKB ansatz for the adiabatic expansion for the field modes. The conformal and axial anomalies thus found are in exact agreement with those obtained from other renormalization methods. This formalism can be considered as an appropriate extension of the techniques originally introduced for scalar fields, applicable to fermions in curved space. © 2015 American Physical Society. Source


Upadhyay S.,Sn Bose National Center For Basic Science
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2013

In this Letter we consider the perturbative quantum gravity on the super-manifold which remains invariant under absolutely anticommuting BRST and anti-BRST transformations. In addition to that the theory posses one more symmetry known as shift symmetry. The BRST invariant Batalin-Vilkovisky (BV) action for perturbative quantum gravity is realized as a translation in Grassmann coordinate. Further we show that the quantum master equation of the BV quantization method at one-loop order can be translated to have a superfield structure for the action. However, the BRST as well as anti-BRST invariant BV action is constructed in superspace with the help of two Grassmann coordinates. © 2013 Elsevier B.V. Source

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