arXiv subjects

Tanay K. Dey

Publications and source records attributed to Tanay K. Dey.

18 recordsLinked to original sources

arXiv2026

Bouncing shellworld embedded in charged AdS spacetime

We investigate the cosmological evolution of a spherical brane within the shellworld (dark bubble) scenario embedded in a five-dimensional charged AdS bulk spacetime. For zero or small value of the brane cosmological constant, the shellworld universe has a nonsingular bouncing and cyclic nature with the bounce induced by the charge parameter of the bulk spacetime. On large value of the brane cosmological constant, the shellworld undergoes a nonsingular bounce and expands eternally. Under certain conditions, the brane bounces outside the bulk horizons, leading to a geometrical resolution of the Cauchy horizon instability present in standard braneworld models. Furthermore, analysis of linear scalar perturbations reveals that test scalar field modes remain regular and non-divergent across the bounce. Finally, we incorporate uniformly distributed long strings in the bulk and demonstrate that the bounce still persists while avoiding the horizon instability.

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arXiv2026

Non-singular Brane/Bubble Cosmologies in the Presence of String Cloud

We investigate the cosmological evolution of a four-dimensional brane/bubble universe embedded in a five-dimensional Anti-de Sitter bulk containing a uniformly distributed cloud of strings. The endpoints of the strings attached to the brane induce an effective matter component in the four-dimensional universe. We derive the Friedmann equations for both the Randall-Sundrum braneworld and the shellworld (dark bubble) scenarios and show that one can obtain a nonsingular bounce in both the brane and bubble universes under certain conditions of the black hole mass and the four-dimensional cosmological constant. Though the bounce due to the spatial curvature occurs outside the black hole horizon, however, the bounce obtained due to the presence of string cloud in the braneworld scenario suffers from the Cauchy horizon instability as the bounce occurs inside the Cauchy horizon of the black hole. In contrast, for the shellworld scenario, the bounce can be made to occur outside the black hole horizon, thereby avoiding the horizon instability. We also analyze the field fluctuations on the brane/bubble and show that the fluctuations remain finite and well-behaved at the bounce point.

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arXiv2026

Transport properties of baryon rich back-reacted thermal plasma with finite 't Hooft coupling correction

In this work, holographic approach has been used to analyse the transport properties of baryon rich back-reacted thermal plasma with finite 't Hooft coupling correction. The dual bulk geometry is charged AdS black hole with higher derivative Gauss-Bonnet (GB) correction and string cloud. Specially, we have studied the nature of drag force, jet quenching parameter, screening length, radial profile and energy loss with respect to different parameters. The drag force and jet quenching parameter are enhanced with GB coupling, baryon and flavor density whereas the screening length reduces with these parameters. The radial profile and energy loss of the rotating quark has also been studied and it is observed that the radial profile decreases with increase in baryon potential and flavor density, temperature and angular frequency, whereas it is enhanced with conjugate momenta and GB coupling. Further, the energy loss of the quark grows with potential and flavor density, velocity and angular frequency and it is suppressed with GB coupling.

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arXiv2025

Hydrodynamical properties of back reacted thermal plasma with finite 't Hooft coupling correction

In this work, holographic approach has been used to analyse the hydrodynamical properties of $\mathcal{N}=4$ Super Yang-Mills thermal plasma with subleading 't Hooft coupling correction and flavour quarks dual to the AdS Gauss-Bonnet gravity in the presence of string cloud. The drag exerted on an external probe quark while translating through the thermal plasma enhances with probe velocity, flavour quark density, temperature and finite coupling correction. The jet quenching parameter gets enhanced on increase of flavour quark density, temperature and finite coupling correction. Quark-antiquark screening length is observed to reduce with rapidity parameter, flavour quark density, finite coupling correction and temperature which suggests an early transition to the thermal plasma phase of QGP. The screening length is found to be larger for the parallel orientation compared to the perpendicular configuration. Finally, the rotational dynamics of the heavy probe quark is studied. The rotational and drag energy loss increases with angular frequency and quark density, but is almost independent of the 't Hooft coupling.

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arXiv2024

Hydrodynamical properties of baryon rich thermal plasma with flavour quarks

In this work, we holographically study the hydrodynamical properties of strongly coupled $\mathcal{N} = 4$ SYM baryon rich thermal plasma with large number of flavour quarks. Specifically, we study the drag force acting on the moving heavy probe quark and corresponding energy loss. We also study the jet quenching parameter, screening length and binding energy of the quark-antiquark pair. Due to the presence of finite baryon density and flavour quarks the drag force, energy loss, jet quenching parameter and binding energy of the quark-antiquark pair are enhanced for the increase in temperature. However, the screening length of the quark-antiquark pair is reduced, leading to the thermal plasma phase being achieved at a lower temperature, which is consistent with the thermal phase diagram of the quark-gluon plasma. We observed that the perpendicular orientation of quark-antiquark pair with respect to the direction of motion deconfined early compare to the parallel orientation once temperature raises.

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arXiv2024

Charged AdS black holes with higher derivative corrections in presence of string cloud

We have obtained charged asymptotically AdS black hole solutions in Einstein Gauss Bonnet gravity in presence of string cloud. It turns out that there exist three black holes in certain range of parameters for small enough chemical potential. However, for large chemical potential, these black holes merge into a single one. The free energy of the black holes is computed from the on shell Euclidean action by subtracting the contribution of an extremal black hole. We have studied the free energy and specific heat of the solutions, which shows that the medium sized black hole is unstable. As an application, we have studied the quark-antiquark potential in the dual gauge theory. This study provides necessary ingredients for study of the dual theories in the context of condensed matter systems.

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arXiv2024

Charged AdS Black Holes in Presence of String Cloud and Cardy-Verlinde Formula

In this study, charged AdS black holes with a string cloud are taken into consideration. We identify three distinct black hole solutions within a specific temperature range, which subsequently merge into a single black hole beyond this range in the case of spherical space with low chemical potential and string density. However, in the case of large chemical potential and string density, only one black hole solution exists for all temperatures. Notably, we observe that for flat and hyperbolic space, there is only one black hole solution irrespective of the chemical potential and string density. By subtracting the contribution of the extremal black hole from the on-shell Euclidean action, the thermodynamical quantities associated with these black holes are calculated. We also investigate the stability of these black holes and find that medium-sized black hole is unstable. In the dual boundary theory side we verify the existence of bound state of quark-antiquark pair. Finally, we establish the Cardy-Verlinde formula for the boundary theory and we observed an additional energy term arising because of the presence of string cloud.

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arXiv2020

AdS black holes with higher derivative corrections in presence of string cloud

We consider asymptotically AdS black hole solutions in presence of string clouds and higher derivative corrections. We find that it admits three black hole solutions within a region of the parameter space. In order to examine the stabilities of these solutions we consider a thermodynamic analysis. Using holography, we have studied the quark-antiquark distance and binding energy in the dual gauge theory.

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arXiv2018

Phase transition of AdS Schwarzschild black hole and gauge theory dual in presence of external string cloud

We study the thermodynamics of AdS-Schwarzschild black hole in the presence of an external string cloud. We observe that, at any temperature, the black hole configuration is stable with non-zero entropy. We further notice that, when the value of the curvature constant equals to one, if the string cloud density has less than a critical value, within a certain range of temperature three black holes configuration exist. One of these black holes is unstable and other two are stable. At a critical temperature, a transition between these two stable black holes takes place which leads us to conclude that the bound state of quark and anti-quark pairs may not exist. By studying the corresponding dual gauge theory we confirm that the instability of the bound state of quark and anti-quark pair in the dual gauge theory.

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arXiv2016

Back reaction effects on the dynamics of heavy probes in heavy quark cloud

We holographically study the effect of back reaction on the hydrodynamical properties of $\mathcal{N} = 4$ strongly coupled super Yang-Mills (SYM) thermal plasma. The back reaction we consider arises from the presence of static heavy quarks uniformly distributed over $\mathcal{N} = 4$ SYM plasma. In order to study the hydrodynamical properties, we use heavy quark as well as heavy quark-antiquark bound state as probes and compute the jet quenching parameter, screening length and binding energy. We also consider the rotational dynamics of heavy probe quark in the back-reacted plasma and analyse associated energy loss. We observe that the presence of back reaction enhances the energy-loss in the thermal plasma. Finally, we show that there is no effect of angular drag on the rotational motion of quark-antiquark bound state probing the back reacted thermal plasma.

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arXiv2012

Mass Deformed L-BLG Theory From ABJ Theory

We construct mass deformed SU(N) L-BLG theory together with $U(M-N)_k$ Chern-Simons theory. This mass deformed L-BLG theory is a low energy world volume theory of a stack of $N$ number of M2-brane far away from $C^4/Z_k$ singularity. We carry out this by defining a special scaling limit of the fields of this theory and simultaneously sending the Chern-Simons level to infinity.

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arXiv2012

Correlators of Giant Gravitons from dual ABJ(M) Theory

We generalize the operators of ABJM theory, given by Schur polynomials, in ABJ theory by computing the two point functions in the free field and at finite $(N_1,N_2)$ limits. These polynomials are then identified with the states of the dual gravity theory. Further, we compute correlators among giant gravitons as well as between giant gravitons and ordinary gravitons through the corresponding correlators of ABJ(M) theory. Finally, we consider a particular non-trivial background produced by an operator with an $\cal R$-charge of $O(N^2)$ and find, in presence of this background, due to the contribution of the non-planar corrections, the large $(N_1,N_2)$ expansion is replaced by $1/(N_1+M)$ and $1/(N_2+M)$ respectively.

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arXiv2011

Exact Large R-charge Correlators in ABJM Theory

We construct a class of operators, given by Schur polynomials, in ABJM theory. By computing two point functions at finite $N$ we confirm these are diagonal for this class of operators in the free field limit. We also calculate exact three and multi point correlators in the zero coupling limit. Finally, we consider a particular nontrivial background produced by an operator with an $R$-charge of $O(N^2$. We show that the nonplanar corrections (which can no longer be neglected, even at large $N$) can be resummed to give a $1/(N+M)$ expansion for correlators computed in this background.

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arXiv2009

Hints of Integrability Beyond the Planar Limit: Nontrivial Backgrounds

The problem of computing the anomalous dimensions of a class of (nearly) half-BPS operators with a large R-charge is reduced to the problem of diagonalizing a Cuntz oscillator chain. Due to the large dimension of the operators we consider, non-planar corrections must be summed to correctly construct the Cuntz oscillator dynamics. These non-planar corrections do not represent quantum corrections in the dual gravitational theory, but rather, they account for the backreaction from the heavy operator whose dimension we study. Non-planar corrections accounting for quantum corrections seem to spoil integrability, in general. It is interesting to ask if non-planar corrections that account for the backreaction also spoil integrability. We find a limit in which our Cuntz chain continues to admit extra conserved charges suggesting that integrability might survive.

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arXiv2009

Correlators Of Operators with a Large R-charge

Correlation functions of operators with a conformal dimension of O(N^2) are not well approximated by the planar limit. The non-planar diagrams, which in the bulk spacetime correspond to string loop corrections, are enhanced by huge combinatorial factors. In this article we show how these loop corrections can be resummed. As a typical example of our results, in the half-BPS background of M maximal giant gravitons we find the usual 1/N expansion is replaced by a 1/(M+N) expansion. Further, we find that there is a simple exact relationship between amplitudes computed in the trivial background and amplitudes computed in the background of M maximal giant gravitons. Finally, we also find strong evidence for the BMN-type sectors suggested in arXiv:0801.4457. The decoupling limit of arXiv:0801.4457 captures the decoupled low energy world volume theory of the intersecting giant graviton system and this theory is weakly coupled even when the original N=4 super Yang-Mills theory is strongly coupled.

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arXiv2009

A note on matrix model with IR cutoff and AdS/CFT

We propose an effective model of strongly coupled gauge theory at finite temperature on $R^3$ in the presence of an infrared cutoff. It is constructed by considering the theory on $S^3$ with an infrared cutoff and then taking the size of the $S^3$ to infinity while keeping the cutoff fixed. This model reproduces various qualitative features expected from its gravity dual.

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arXiv2007

Phase transitions in higher derivative gravity and gauge theory: R-charged black holes

This is a continuation of our earlier work where we constructed a phenomenologically motivated effective action of the boundary gauge theory at finite temperature and finite gauge coupling on $S^3 \times S^1$. In this paper, we argue that this effective action qualitatively reproduces the gauge theory representing various bulk phases of R-charged black hole with Gauss-Bonnet correction. We analyze the system both in canonical and grand canonical ensemble.

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arXiv2007

Phase Transitions in Higher Derivative Gravity

This paper deals with black holes, bubbles and orbifolds in Gauss-Bonnet theory in five dimensional anti de Sitter space. In particular, we study stable, unstable and metastable phases of black holes from thermodynamical perspective. By comparing bubble and orbifold geometries, we analyse associated instabilities. Assuming AdS/CFT correspondence, we discuss the effects of this higher derivative bulk coupling on a specific matrix model near the critical points of the boundary gauge theory at finite temperature. Finally, we propose another phenomenological model on the boundary which mimics various phases of the bulk space-time.

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