Sameer Murthy
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View article: Black hole microstate counting from the gravitational path integral
Black hole microstate counting from the gravitational path integral Open
A bstract Reproducing the integer count of black hole microstates from the gravitational path integral is an important problem in quantum gravity. In this paper, we show that, by using supersymmetric localization, the gravitational path in…
View article: Localization and wall-crossing of giant graviton expansions in AdS5
Localization and wall-crossing of giant graviton expansions in AdS5 Open
A bstract The $$ \frac{1}{2} $$ -BPS indices of $$ \mathcal{N} $$ = 4 Super Yang-Mills theory with unitary, orthogonal, and symplectic groups all admit q -expansions suggesting an interpretation in terms of D- branes in the dual bulk…
View article: Multicentered black hole saddles for supersymmetric indices
Multicentered black hole saddles for supersymmetric indices Open
The supersymmetric index in string theory can sometimes have a discontinuous integer-valued jump at co-dimension one surfaces in moduli space called walls of marginal stability. When the index counts black hole microstates, crossing such w…
View article: Revisiting the logarithmic corrections to the black hole entropy
Revisiting the logarithmic corrections to the black hole entropy Open
A bstract Logarithmic corrections to the entropy of extremal black holes have been successfully used to accurately match degeneracies from microscopic constructions to calculations of the gravitational path integral. In this paper, we revi…
View article: Localization of strings on group manifolds
Localization of strings on group manifolds Open
We compute the partition function of the WZW model with target a compact Lie group $G$ by adapting a method used by Choi and Takhtajan to compute the heat kernel of the group manifold. The basic idea is to compute the partition function of…
View article: The gravitational index of 5d black holes and black strings
The gravitational index of 5d black holes and black strings Open
A bstract The supersymmetric index of 5 d black strings and spinning black holes in M-theory is related to that of 4 d black holes in type IIA supergravity when both theories are compactified on the same Calabi-Yau threefold. We find the f…
View article: The gravitational index of 5d black holes and black strings
The gravitational index of 5d black holes and black strings Open
A bstract The supersymmetric index of 5 d black strings and spinning black holes in M-theory is related to that of 4 d black holes in type IIA supergravity when both theories are compactified on the same Calabi-Yau threefold. We find the f…
View article: The gravitational index and allowable complex metrics
The gravitational index and allowable complex metrics Open
We study the Konstevich–Segal–Witten criterion for allowable complex metrics, in the context of the gravitational path integral corresponding to the supersymmetric index. In various theories of supergravity in asymptotically flat and asymp…
View article: Strings and near-extremal black holes in theories with large $\mathcal{N}=4$ superconformal symmetry
Strings and near-extremal black holes in theories with large $\mathcal{N}=4$ superconformal symmetry Open
We study the one-loop partition function of superstrings in the $\mathrm{AdS}_3 \times \mathbf{S}^3 \times \mathbf{S}^3 \times \mathbf{S}^1$ background. Specifically, we show that the supergravity spectrum, which contains non-chiral primar…
View article: Strings in AdS3: one-loop partition function and near-extremal BTZ thermodynamics
Strings in AdS3: one-loop partition function and near-extremal BTZ thermodynamics Open
A bstract We revisit the computation of the string partition function in AdS 3 focussing on the appearance of spacetime (super) symmetries. We show how the asymptotic symmetries of the AdS 3 spacetime, which generate the boundary (super) V…
View article: New forms of attraction: attractor saddles for the black hole index
New forms of attraction: attractor saddles for the black hole index Open
A bstract The count of microstates for supersymmetric black holes is typically obtained from a supersymmetric index in weakly-coupled string theory. We find the saddles in the gravitational path integral corresponding to this index in a ge…
View article: The gravitational index and allowable complex metrics
The gravitational index and allowable complex metrics Open
We study the Konstevich--Segal--Witten criterion for allowable complex metrics, in the context of the gravitational path integral corresponding to the supersymmetric index. In various theories of supergravity in asymptotically flat and asy…
View article: Localization and wall-crossing of giant graviton expansions in AdS$_5$
Localization and wall-crossing of giant graviton expansions in AdS$_5$ Open
The $\frac12$-BPS indices of $\mathcal{N}=4$ Super Yang-Mills theory with unitary, orthogonal, and symplectic groups all admit $q$-expansions suggesting an interpretation in terms of D-branes in the dual bulk AdS$_5$ string theories. We pr…
View article: Gravitational index of the heterotic string
Gravitational index of the heterotic string Open
A bstract The fundamental heterotic string has a tower of BPS states whose supersymmetric index has an exponential growth in the charges. We construct the saddle-point of the gravitational path integral corresponding to this index. The sad…
View article: Strings in AdS$_3$: one-loop partition function and near-extremal BTZ thermodynamics
Strings in AdS$_3$: one-loop partition function and near-extremal BTZ thermodynamics Open
We revisit the computation of the string partition function in AdS$_3$ focussing on the appearance of spacetime (super) symmetries. We show how the asymptotic symmetries of the AdS$_3$ spacetime, which generate the boundary (super) Virasor…
View article: Gravitational index of the heterotic string
Gravitational index of the heterotic string Open
The fundamental heterotic string has a tower of BPS states whose supersymmetric index has an exponential growth in the charges. We construct the saddle-point of the gravitational path integral corresponding to this index. The saddle-point …
View article: The giant graviton expansion in $AdS_5 \times S^5$
The giant graviton expansion in $AdS_5 \times S^5$ Open
The superconformal index of $\frac12$-BPS states of $N=4$ U(N) super Yang-Mills theory has a known infinite $q$-series expression with successive terms suppressed by $q^N$. We derive a holographic bulk interpretation of this series by eval…
View article: New forms of attraction: Attractor saddles for the black hole index
New forms of attraction: Attractor saddles for the black hole index Open
The count of microstates for supersymmetric black holes is typically obtained from a supersymmetric index in weakly-coupled string theory. We find the saddles in the gravitational path integral corresponding to this index in a general theo…
View article: Localization on AdS3 × S2. Part I. The 4d/5d connection in off-shell Euclidean supergravity
Localization on AdS3 × S2. Part I. The 4d/5d connection in off-shell Euclidean supergravity Open
A bstract We begin to develop the formalism of localization for the functional integral of supergravity on AdS 3 × S 2 . We show how the condition of supersymmetry in the Euclidean ℍ 3 / ℤ × S 2 geometry naturally leads to a twist of the S…
View article: Supersymmetric phases of AdS4/CFT3
Supersymmetric phases of AdS4/CFT3 Open
A bstract We exhibit an infinite family of supersymmetric phases in the three-dimensional ABJM superconformal field theory and the dual asymptotically AdS 4 gravity. They are interpreted as partially deconfined phases which generalize the …
View article: Black holes and modular forms in string theory
Black holes and modular forms in string theory Open
The study of black holes in string theory has led to the discovery of deep and surprising connections between black holes and modular forms -- which are two classical, a priori unrelated, subjects. This article explains the main physical a…
View article: Modular symmetry of massive free fermions
Modular symmetry of massive free fermions Open
We construct an infinite set of conserved tensor currents of rank $2n$, $n=1,2,\dots$, in the two-dimensional theory of free massive fermions, which are bilinear in the fermionic fields. The one-point functions of these currents on the tor…
View article: Localization on $AdS_3 \times S^2$ I: the 4d/5d connection in off-shell Euclidean supergravity
Localization on $AdS_3 \times S^2$ I: the 4d/5d connection in off-shell Euclidean supergravity Open
We begin to develop the formalism of localization for the functional integral of supergravity on $AdS_3 \times S^2$. We show how the condition of supersymmetry in the Euclidean $\mathbb{H}^3/\mathbb{Z} \times S^2$ geometry naturally leads …
View article: Supersymmetric phases of AdS$_4$/CFT$_3$
Supersymmetric phases of AdS$_4$/CFT$_3$ Open
We exhibit an infinite family of supersymmetric phases in the three-dimensional ABJM superconformal field theory and the dual asymptotically AdS$_4$ gravity. They are interpreted as partially deconfined phases which generalize the confined…
View article: Black hole microstate counting from the gravitational path integral
Black hole microstate counting from the gravitational path integral Open
Reproducing the integer count of black hole micro-states from the gravitational path integral is an important problem in quantum gravity. In this paper, we show that, by using supersymmetric localization, the gravitational path integral fo…
View article: Revisiting the Logarithmic Corrections to the Black Hole Entropy
Revisiting the Logarithmic Corrections to the Black Hole Entropy Open
Logarithmic corrections to the entropy of extremal black holes have been successfully used to accurately match degeneracies from microscopic constructions to calculations of the gravitational path integral. In this paper, we revisit the pr…
View article: Unitary matrix models, free fermion ensembles, and the giant graviton expansion
Unitary matrix models, free fermion ensembles, and the giant graviton expansion Open
We consider a class of matrix integrals over the unitary group $U(N)$ with an infinite set of couplings characterized by a series $f(q)=\sum_{n \ge 1} a_n q^n$, with $a_n \in \mathbb{Z}$. Such integrals arise in physics as the partition fu…
View article: The growth of the $\frac{1}{16}$-BPS index in 4d $\mathcal{N}=4$ SYM
The growth of the $\frac{1}{16}$-BPS index in 4d $\mathcal{N}=4$ SYM Open
We study the Hamiltonian index of $\frac{1}{16}$-BPS operators in 4d $\mathcal{N}=4$ U(N) super Yang-Mills (SYM) theory numerically for $N=2\,,\dots,10$. We show that the large-charge asymptotics agree with analytic results in the Cardy-li…