arXiv subjects

Sudhaker Upadhyay

Publications and source records attributed to Sudhaker Upadhyay.

At least 73 records · Page 4Linked to original sources

arXiv2019

Thermal fluctuations to thermodynamics of non-rotating BTZ black hole

In this paper, we discuss the effect of small statistical thermal fluctuations around the equilibrium on the thermodynamics of small non-rotating BTZ black hole. This is done by evaluating the leading-order corrections to the thermodynamical equation of states, namely, entropy, free energy, internal energy, pressure, enthalpy, Gibbs free energy and specific heat quantitatively. In order to analyze the effect of perturbations on the thermodynamics, we plot various graphs and compare corrected and non-corrected thermodynamic quantities with respect to event horizon radius of non-rotating BTZ black hole. We also derive the first-order corrections to isothermal compressibility.

gr-qc↗

arXiv2019

Lorentz-violating gaugeon formalism for rank-2 tensor theory

We develop a BRST symmetric gaugeon formalism for the Abelian rank-2 antisymmetric tensor field in the Lorentz breaking framework. The Lorentz breaking is achieved here by considering a proper subgroup of Lorentz group together with translation. In this scenario, the gaugeon fields together with the standard fields of the Abelian rank-2 antisymmetric tensor theory get mass. In order to develop the gaugeon formulation for this theory in VSR, we first introduce a set of dipole vector fields as a quantum gauge freedom to the action. In order to quantize the dipole vector fields, the VSR-modified gauge-fixing and corresponding ghost action are constructed as the classical action is invariant under a VSR-modified gauge transformation. Further, we present a Type I gaugeon formalism for the Abelian rank-2 antisymmetric tensor field theory in VSR. The gauge structures of Fock space constructed with the help of BRST charges are also discussed.

hep-th↗

arXiv2019

Corrections to Scattering Processes due to Minimal Measurable Length

In this paper, we will analyze the short distance corrections to low energy scattering. They are produced because of an intrinsic extended structure of the background geometry of spacetime. It will be observed that the deformation produced by a minimal measurable length can have low energy consequences, if this extended structure occurs at a scale much larger than the Planck scale. We explicitly calculate short distance corrections to the Green function of the deformed Lippmann-Schwinger equation, and to the conserved currents for these processes. We then use them to analyze the pre-asymptotic corrections to the differential scattering flux at finite macroscopically small distances.

hep-th↗

arXiv2018

Logarithmic corrected Van der Waals black holes in higher dimensional AdS space

In this paper, we consider AdS black hole in $d$-dimensional space-time and calculate the logarithmic corrected thermodynamics quantities. We study the effects of thermal fluctuations on the thermodynamics of higher dimensional AdS black hole. We exploit such logarithmic corrected quantities to construct Van der Walls black holes solution and study the effects of logarithmic correction on the Van der Waals black holes. We also investigate the effect of thermal fluctuations on the equation of state. We find that the Van der Waals black hole is completely stable in the presence of the logarithmic correction.

gr-qc↗

arXiv2018

Leading-order corrections to charged rotating AdS black holes thermodynamics

In this paper, we consider a charged rotating AdS black holes in four dimensions and study the effects of leading-order thermal corrections on the thermodynamics of such system explicitly. The first-order corrected thermodynamical quantities also satisfy the first-law of thermodynamics of the black holes. The holographic duality between the charged rotating AdS black holes and Van der Waals fluid is also emphasized through the $P-v$ diagram. Finally, we study the effects of the leading-order thermal corrections on the stability of the charged rotating black holes.

gr-qc↗

arXiv2018

Thermodynamics and phase transitions of galactic clustering in higher-order Modified Gravity

We study the thermodynamics of galactic clustering under the higher-order corrected Newtonian dynamics. The clustering of galaxies is considered as a gravitational phase transition. In order to study the effects of higher-order correction to the thermodynamics of gravitational system, we compute more exact equations of state. Moreover, we investigate the corrected probability distribution function for such gravitating system. A relation between order parameter and the critical temperature is also established.

gr-qc↗

arXiv2018

Thermal fluctuations of charged black holes in gravity's rainbow

Quantum fluctuation effects have an irrefutable role in high energy physics. Such fluctuation can be often regarded as a correction of infrared (IR) limit. In this paper, the effects of the first-order correction of entropy, caused by thermal fluctuation, on the thermodynamics of charged black holes in gravity's rainbow will be discussed. It will be shown that such correction has profound contributions to high energy limit of thermodynamical quantities, stability conditions of the black holes and interestingly has no effect on thermodynamical phase transitions. The coupling between gravity's rainbow and the first-order correction will be addressed. In addition, the measurement of entropy as a function of fluctuation of temperature will be done and it will be shown that de Sitter (dS) case enforces an upper limit on the values of temperature and produces cyclic like diagrams. While for the anti-de Sitter (AdS) case, a lower limit on the entropy is provided and although for special cases a cyclic like behavior could be observed, no upper or lower limit exists for the temperature. In addition, a comparison between non-correction and correction included cases on the thermodynamical properties of solutions will also be discussed and the effects of the first-order correction will be highlighted. It will be shown that the first-order correction provides the solutions with larger classes of thermal stability conditions which may result into existence of a larger number of thermodynamical structures for the black holes.

gr-qc↗

arXiv2017

Large Distance Modification of Newtonian Potential and Structure Formation in Universe

In this paper, we study the effects of super-light brane world perturbative modes on structure formation in our universe. As these modes modify the large distance behavior of Newtonian potential, they effect the clustering of a system of galaxies. So, we explicitly calculate the clustering of galaxies interacting through such a modified Newtonian potential. We use a suitable approximation for analyzing this system of galaxies, and discuss the validity of such approximations. We observe that such corrections also modify the virial theorem for such a system of galaxies.

gr-qc↗

arXiv2017

Clustering of Galaxies with f(R) gravity

Based on thermodynamics, we discuss the galactic clustering of expanding Universe by assuming the gravitational interaction through the modified Newton's potential given by $f(R)$ gravity. We compute the corrected $N$-particle partition function analytically. The corrected partition function leads to more exact equations of states of the system. By assuming that system follows quasi-equilibrium, we derive the exact distribution function which exhibits the $f(R)$ correction. Moreover, we evaluate the critical temperature and discuss the stability of the system. We observe the effects of correction of $f(R)$ gravity on the power law behavior of particle-particle correlation function also. In order to check feasibility of an $f(R)$ gravity approach to the clustering of galaxies, we compare our results with an observational galaxy cluster catalog.

astro-ph.CO↗

arXiv2017

Hawking Radiation Power Equations for Black Holes

We derive the Hawking radiation power equations for black holes in asymptotically flat, asymptotically Anti-de Sitter (AdS) and asymptotically de Sitter (dS) black holes, This is done by using the greybody factor for these black holes. We observe that the radiation power equation for asymptotically flat black holes, corresponding to greybody factor at low frequency, depends on both the Hawking temperature and the horizon radius. However, for the greybody factors at asymptotic frequency, it only depends on the Hawking temperature. We also obtain the power equation for asymptotically AdS black holes both below and above the critical frequency. The radiation power equation for at asymptotic frequency is same for both Schwarzschild AdS and Reissner-Nordström AdS solutions and only depends on the Hawking temperature. We also discuss the power equation for asymptotically dS black holes at low frequency, for both even or odd dimensions.

gr-qc↗

arXiv2017

Quantum corrections to thermodynamics of quasitopological black holes

Based on the modification to area-law due to thermal fluctuation at small horizon radius, we investigate the thermodynamics of charged quasitopological and charged rotating quasitopological black holes. In particular, we derive the leading-order corrections to the Gibbs free energy, charge and total mass densities. In order to analyse the behavior of the thermal fluctuations on the thermodynamics of small black holes, we draw a comparative analysis between the first-order corrected and original thermodynamical quantities. We also examine the stability and bound points of such black holes under effect of leading-order corrections.

gr-qc↗

arXiv2017

Thermal Fluctuations in a Hyperscaling Violation Background

In this paper, we study the effect of thermal fluctuations on the thermodynamics of a black geometry with hyperscaling violation. These thermal fluctuations in the thermodynamics of this system are produced from quantum corrections of geometry describing this system. We discuss the stability of this system using specific heat and the entire Hessian matrix of the free energy. We will analyze the effects of thermal fluctuations on the stability of this system. We also analyze the effects of thermal fluctuations on the criticality of the Hyperscaling violation background.

hep-th↗

arXiv2017

Cosmic string in gravity's rainbow

In this paper, we study the various cylindrical solutions (cosmic strings) in gravity's rainbow scenario. In particular, we calculate the gravitational field equations corresponding to energy-dependent background. Further, we discuss the possible Kasner, quasi-Kasner and non-Kasner exact solutions of the field equations. In this framework, we find that quasi-Kasner solutions can not be realized in gravity's rainbow. Assuming only time-dependent metric functions, we also analyse the time-dependent vacuum cosmic strings in gravity's rainbow, which are completely different than the other GR solutions.

gr-qc↗

arXiv2017

Finite BRST Mapping in Higher Derivative Models

We continue the study of finite field dependent BRST (FFBRST) symmetry in the quantum theory of gauge fields. An expression for the Jacobian of path integral measure is presented, depending on a finite field-dependent parameter, and the FFBRST symmetry is then applied to a number of well-established quantum gauge theories in a form which includes higher-derivative terms. Specifically, we examine the corresponding versions of the Maxwell theory, non-Abelian vector field theory, and gravitation theory. We present a systematic mapping between different forms of gauge-fixing, including those with higher-derivative terms, for which these theories have better renormalization properties. In doing so, we also provide the independence of the S-matrix from a particular gauge-fixing with higher derivatives. Following this method, a higher-derivative quantum action can be constructed for any gauge theory in the FFBRST framework.

hep-th↗

arXiv2017

Clustering of Galaxies with Dynamical Dark Energy

In this paper, we study thermodynamics of the cluster of galaxies under the effect of dynamical dark energy. We evaluate the configurational integral for interacting system of galaxies in an expanding universe by including the effects produced by the varying $Λ$. The gravitational partition function is obtained using this configuration integral. We obtain thermodynamics quantities in canonical ensemble which depend on time and investigate the second law of thermodynamics. We also calculate the distribution function in grand canonical ensemble. The time evolution of the clustering parameter of galaxies is investigated for the time dependent (dynamical) dark energy. We conclude that the second law of thermodynamics is valid for the total system of cluster of galaxies and dynamical dark energy. We calculate correlation function and show that our model is very close to Peebles's power law, in agreement with the N-body simulation. It is observed that thermodynamics quantities depend on the modified clustering parameter for this system of galaxies.

gr-qc↗

arXiv2017

Thermodynamics and galactic clustering with a modified gravitational potential

Based on thermodynamics, we study the galactic clustering of an expanding Universe by considering the logarithmic and volume (quantum) corrections to Newton's law along with the repulsive effect of a harmonic force induced by the cosmological constant ($Λ$) in the formation of the large scale structure of the Universe. We derive the $N$-body partition function for extended-mass galaxies (galaxies with halos) analytically. For this partition function, we compute the exact equations of states, which exhibit the logarithmic, volume and cosmological constant corrections. In this setting, a modified correlation (clustering) parameter (due to these corrections) emerges naturally from the exact equations of state. We compute a corrected grand canonical distribution function for this system. Furthermore, we obtain a deviation in differential forms of the two-point correlation functions for both the point-mass and extended-mass cases. The consequences of these deviations on the correlation function's power law are also discussed.

gr-qc↗

arXiv2017

Construction of a Massive ABJM Theory Without Higgs Superfields

A massive Aharony-Bergman-Jafferis-Maldacena (ABJM) model in $\mathcal{N} =1$ superspace is analysed by considering a Proca type mass term into the most general Faddeev-Popov action in a covariant gauge. The presence of mass term breaks the original BRST and anti-BRST invariance of the model. Further, the symmetry of the massive ABJM model is restored by extending the BRST and anti-BRST transformations. We show that the supergauge dependence of generating functional for connected diagrams occurs in presence of mass and ghost-anti-ghost condensates in the theory.

hep-th↗

arXiv2017

Lorentz Violating $p$-form Gauge Theories in Superspace

Very special relativity (VSR) keeps the main features of special relativity but breaks rotational invariance due to an intrinsic preferred direction. We study the VSR modified extended BRST and anti-BRST symmetry of the Batalin-Vilkovisky (BV) actions corresponding to the $p=1,2,3$-form gauge theories. Within VSR framework, we discuss the extended BRST invariant and extended BRST and anti-BRST invariant superspace formulations for these BV actions. Here we observe that the VSR modified extended BRST invariant BV actions corresponding to the $p=1,2,3$-form gauge theories can be written manifestly covariant manner in a superspace with one Grassmann coordinate. Moreover, two Grassmann coordinates are required to describe the VSR modified extended BRST and extended anti-BRST invariant BV actions in a superspace. These results are consistent with the Lorentz invariant (special relativity) formulation.

hep-th↗