arXiv subjects

Mangesh Mandlik

Publications and source records attributed to Mangesh Mandlik.

13 recordsLinked to original sources

arXiv2026

A fluid dual to large $D$ membrane paradigm at first subleading order

The large $D$ membrane paradigm establishes a duality between the dynamics of black holes and the evolution of a codimension-one timelike membrane in a non-gravitational background. In this work, we formulate the relativistic fluid dynamics dual to an uncharged black hole in asymptotically flat spacetime at the first subleading order in the $1/D$ expansion. Due to the absence of a timelike asymptotic boundary, unlike in AdS/CFT fluid-gravity duality, we construct an effective fluid intrinsically on the dynamical membrane, whose equations of motion are exactly equivalent to the subleading order membrane equations. By performing this fluid-dynamical analysis in the Landau frame, we show that the system behaves as a fluid influenced by an effective background force. Out-of-equilibrium viscous effects emerge naturally, allowing us to extract the fluid transport coefficients directly from the bulk viscous pressure and shear stress tensor. Furthermore, the fluid exhibits a negative pressure, capturing the intrinsic surface tension of the $(D-1)$-dimensional membrane worldvolume.

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arXiv2026

A fluid dual to the charged large D membrane paradigm

According to the formulation of the charged large $D$ membrane paradigm, an arbitrary dynamic black hole solution to a theory of gravity with a $U(1)$ gauge field is dual to the dynamics of a membrane in a non-gravitational background. This membrane is endowed with a stress-energy tensor and a charge current, whose conservation equations govern its dynamics. In this work, we demonstrate that the dynamics of these membrane configurations (at the leading nontrivial order in $1/D$) can be mapped to a relativistic charged fluid, establishing a correspondence for asymptotically flat black holes with a particular class of fluid systems. Unlike the standard AdS/Hydrodynamics correspondence, this dual fluid does not reside on an asymptotic boundary, but is localised strictly on the non-gravitational membrane worldvolume. By evaluating the system in both the Eckart and Landau frames, we systematically extract the out-of-equilibrium transport coefficients. We find that the fluid is governed by a negative effective thermal conductivity and a negative heat capacity. This mechanism provides a hydrodynamic interpretation of thermodynamic stability, effectively translating the previously established quasinormal mode damping of the large-$D$ Reissner-Nordström geometry into the language of fluid dynamics.

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arXiv2026

The extremal Reissner-Nordström throat from non extremal near horizon expansions

The near horizon region of a non extremal black hole has a universal Rindler form, but the strict horizon limit is not an ordinary Lorentzian geometry. In the String Carroll expansion of this non extremal near horizon metric,the transverse angular directions form a base and the time-radial Rindler directions appear as a distinguished two-dimensional longitudinal sector fibered over this base. We study how this String Carroll expansion behaves for the Reissner-Nordström (RN) black hole as the extremal limit is approached, where the expected near horizon geometry is the Lorentzian $AdS_2 \times S^2$ throat. We show that while for the four-dimensional non extremal RN geometry, the String Carroll expansion correctly captures the near horizon Rindler region, it is not sufficient to recover the extremal $AdS_2 \times S^2$ throat. The reason is that the higher order terms, which are suppressed in the String Carroll expansion, become essential in the extremal limit. We show that in Eddington-Finkelstein coordinates, the required contribution appears at second order and restores the radial dependence needed for the $AdS_2$ geometry. The extremal $AdS_2 \times S^2$ throat is then obtained as the zero-temperature limit of the scaled throat geometry. In static coordinates, the temporal sector of the extremal throat geometry can be obtained from a second order near horizon expansion, but the radial sector cannot be obtained from any finite order truncation and requires contributions from all orders in the near horizon expansion.

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arXiv2024

3d Carrollian Chern-Simons theory and 2d Yang-Mills

With the goal of building a concrete co-dimension one holographically dual field theory for four dimensional asymptotically flat spacetimes (4d AFS) as a limit of AdS$_4$/CFT$_3$, we begin an investigation of 3d Chern-Simons matter (CSM) theories in the Carroll regime. We perform a Carroll (speed of light $c\to0$) expansion of the relativistic Chern-Simons action coupled to a massless scalar and obtain Carrollian CSM theories, which we show are invariant under the infinite dimensional 3d conformal Carroll or 4d Bondi-van der Burg-Metzner-Sachs (BMS$_4$) symmetries, thus making them putative duals for 4d AFS. Concentrating on the leading-order electric Carroll CSM theory, we perform a null reduction of the 3d theory. Null reduction is a procedure to obtain non-relativistic theories from a higher dimensional relativistic theory. Curiously, null reduction of a Carrollian theory yields a relativistic lower-dimensional theory. We work with $SU(N) \times SU(M)$ CS theory coupled to bi-fundamental matter and show that when $N=M$, we obtain (rather surprisingly) a 2d Euclidean Yang-Mills theory after null reduction. We also comment on the reduction when $N \neq M$ and possible connections of the null-reduced Carroll theory to a candidate 2d Celestial CFT.

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arXiv2024

Strings near black holes are Carrollian

We demonstrate that strings near the horizon of a Schwarzschild black hole, when viewed by a stationary observer at infinity, probe a string Carroll geometry, where the effective lightspeed is given by the distance from the horizon. We expand the Polyakov action in powers of this lightspeed to find a theory of Carrollian strings. We show that the string shrinks to a point to leading order near the horizon, which follows a null geodesic in a two-dimensional Rindler space. At the next-to-leading order the string oscillates in the embedding fields associated with the near-horizon two-sphere.

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arXiv2021

Tensionless Tales: Vacua and Critical Dimensions

Recently, a careful canonical quantisation of the theory of closed bosonic tensionless strings has resulted in the discovery of three separate vacua and hence three different quantum theories that emerge from this single classical tensionless theory. In this note, we perform lightcone quantisation with the aim of determination of the critical dimension of these three inequivalent quantum theories. The satisfying conclusion of a rather long and tedious calculation is that one of vacua does not lead to any constraint on the number of dimensions, while the other two give $D=26$. This implies that all three quantum tensionless theories can be thought of as consistent sub-sectors of quantum tensile bosonic closed string theory.

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arXiv2020

Black Rings in Large $D$ Membrane Paradigm at the First Order

Black rings are the black objects found in $D$ spacetime dimensional gravity when $D \geq 5$. These have event horizon topology $S^{D-3}\times S^1$. In this work the solutions of the large $D$ membrane paradigm dual to stationary black rings in Einstein-Maxwell theory with or without cosmological constant are studied. It is shown that the first order membrane equations can only admit static asymptotically flat black rings, and the equilibrium angular velocity for the asymptotically AdS black rings at large $D$ was obtained. The thermodynamic and dynamic stability of the asymptotically flat black ring solutions is studied. The apparent shortcomings of some of these results are argued to be curable within the large $D$ membrane paradigm framework.

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arXiv2020

de Sitter Static Black Ring in Large $D$ Membrane Paradigm at the Second Order

It was shown in arXiv:2006.16163 that the effective stationary membrane equations from the large $D$ membrane paradigm at the first order admit black ring solutions in flat and AdS cases, but the de Sitter solution obtained in arXiv:0806.1954 lies outside the domain of their applicability. In this short note the static de Sitter black ring is obtained from the second order membrane paradigm, and it satisfies the equilibrium condition for the thin ring solution of arXiv:0806.1954. This provides a segue into the stationary black rings at the second order.

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arXiv2018

Stationary Solutions from the Large D Membrane Paradigm

It has recently been shown that the dynamics of black holes in large number of dimensions D can be recast as the dynamics of a probe membrane propagating in the background spacetime which solves Einstein equations without matter. The equations of motion of this membrane are simply the statement of conservation of the stress tensor and charge current defined on this membrane. In this paper we obtain the effective equations of motion for stationary membranes in any empty background both in presence and absence of charge. It turns out that the thermodynamic quantities associated with the stationary membranes that satisfy these effective equations also satisfy the first law of black hole thermodynamics. These stationary membrane equations have some interesting solutions such as charged rotating black holes in flat and AdS backgrounds as well as black ring solutions in large D.

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arXiv2017

Currents and Radiation from the large $D$ Black Hole Membrane

It has recently been demonstrated that black hole dynamics in a large number of dimensions $D$ reduces to the dynamics of a codimension one membrane propagating in flat space. In this paper we define a stress tensor and charge current on this membrane and explicitly determine these currents at low orders in the expansion in $\frac{1}{D}$. We demonstrate that dynamical membrane equations of motion derived in earlier work are simply conservation equations for our stress tensor and charge current. Through the paper we focus on solutions of the membrane equations which vary on a time scale of order unity. Even though the charge current and stress tensor are not parametrically small in such solutions, we show that the radiation sourced by the corresponding membrane currents is generically of order $\frac{1}{D^D}$. In this regime it follows that the `near horizon' membrane degrees of freedom are decoupled from asymptotic flat space at every perturbative order in the $\frac{1}{D}$ expansion. We also define an entropy current on the membrane and use the Hawking area theorem to demonstrate that the divergence of the entropy current is point wise non negative. We view this result as a local form of the second law of thermodynamics for membrane motion.

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arXiv2016

A Charged Membrane Paradigm at Large D

We study the effective dynamics of black hole horizons in Einstein-Maxwell theory in a large number of spacetime dimensions $D$. We demonstrate that horizon dynamics may be recast as a well posed initial value problem for the motion of a codimension one non gravitational membrane moving in flat space. The dynamical degrees of freedom of this membrane are its shape, charge density and a divergence free velocity field. We determine the equations that govern membrane dynamics at leading order in the large $D$ expansion. Our derivation of the membrane equations assumes that the solution preserves an SO$(D-p-2)$ isometry with $p$ held fixed as $D$ is taken to infinity. However we are able to cast our final membrane equations into a completely geometric form that makes no reference to this symmetry algebra.

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arXiv2015

Poles in the $S$-Matrix of Relativistic Chern-Simons Matter theories from Quantum Mechanics

An all orders formula for the $S$-matrix for 2 $\rightarrow$ 2 scattering in large N Chern-Simons theory coupled to a fundamental scalar has recently been conjectured. We find a scaling limit of the theory in which the pole in this $S$-matrix is near threshold. We argue that the theory must be well described by non-relativistic quantum mechanics in this limit, and determine the relevant Schroedinger equation. We demonstrate that the $S$-matrix obtained from this Schroedinger equation agrees perfectly with this scaling limit of the relativistic $S$-matrix; in particular the pole structures match exactly. We view this matching as a nontrivial consistency check of the conjectured field theory $S$-matrix.

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arXiv2015

Unitarity, Crossing Symmetry and Duality of the S-matrix in large N Chern-Simons theories with fundamental matter

We present explicit computations and conjectures for $2 \to 2$ scattering matrices in large $N$ {\it $U(N)$} Chern-Simons theories coupled to fundamental bosonic or fermionic matter to all orders in the 't Hooft coupling expansion. The bosonic and fermionic S-matrices map to each other under the recently conjectured Bose-Fermi duality after a level-rank transposition. The S-matrices presented in this paper may be regarded as relativistic generalization of Aharonov-Bohm scattering. They have unusual structural features: they include a non analytic piece localized on forward scattering, and obey modified crossing symmetry rules. We conjecture that these unusual features are properties of S-matrices in all Chern-Simons matter theories. The S-matrix in one of the exchange channels in our paper has an anyonic character; the parameter map of the conjectured Bose-Fermi duality may be derived by equating the anyonic phase in the bosonic and fermionic theories.

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