Prahar Mitra
Current Organizations / Institutes
The organizations/institutes from the scholar's latest article
Previous Organizations / Institutes
The organizations / institutes from the scholar's other articles in the past ten years
Research Subjects
Prahar Mitra has a total of 30 co-authors. Here are the top co-authors by number of shared publications:
- Temple He
California Institute of Technology
10 shared publications - Jorge E. Santos
University of Cambridge
4 shared publications - Oscar Joao Campos Dias
University of Southampton
4 shared publications - Andrew Strominger
Harvard University
3 shared publications - Daniel Kapec
Harvard University
3 shared publications Temple He
Walter Burke Institute for Theoretical Physics
3 shared publications
Latest Publications
- Open Access
- 5 June 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (6) , 1-64
Charged rotating hairy black holes in AdS5 × S5: unveiling their secrets
Using a mix of analytical and numerical methods, we construct new rotating, charged “hairy” black hole solutions of D = 5, $$ \mathcal{N} $$ = 8 gauged supergravity that are dual, via the AdS/CFT correspondence, to thermal states in D = 4, $$ \mathcal{N} $$ = 4 SYM at finite chemical and angular potential, thereby complementing and extending the results of [1–3]. These solutions uplift to asymptotically AdS5 × S 5 solutions of Type IIB supergravity with equal angular momenta along AdS5 (J = J 1 = J 2) and S 5 (Q = Q 1 = Q 2 = Q 3). As we lower the mass E at fixed Q and J, the known Cvetič-Lü-Pope (CLP) black holes are unstable to scalar condensation and the hairy black holes constructed here emerge as novel solutions associated to the instability. In the region of phase space where the CLP and hairy black holes coexist, the hairy black holes dominate the microcanonical ensemble and, therefore, describe a new thermodynamic phase of SYM. The hairy black holes extend beyond the CLP extremality surface all the way to the BPS surface, defined by E = 3Q + 2J/L. Through a combination of analytical and numerical techniques, we argue that the BPS limit of the hairy black holes is a singular, horizonless solution, and not a new two-parameter family of BPS black holes that extend the known one-parameter Gutowski-Reall (GR) black hole solution, in contradiction with the conjectures of [1, 2]. To further support our conclusions, we perform a near-horizon analysis of the BPS equations and argue that they do not admit any regular solutions with an horizon.- 5 June 2025
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2025 (6) , 1-64
Open AccessCharged rotating hairy black holes in AdS5 × S5: unveiling their secrets
Using a mix of analytical and numerical methods, we construct new rotating, charged “hairy” black hole solutions of D = 5, $$ \mathcal{N} $$ = 8 gauged supergravity that are dual, via the AdS/CFT correspondence, to thermal states in D = 4, $$ \mathcal{N} $$ = 4 SYM at finite chemical and angular potential, thereby complementing and extending the results of [1–3]. These solutions uplift to asymptotically AdS5 × S 5 solutions of Type IIB supergravity with equal angular momenta along AdS5 (J = J 1 = J 2) and S 5 (Q = Q 1 = Q 2 = Q 3). As we lower the mass E at fixed Q and J, the known Cvetič-Lü-Pope (CLP) black holes are unstable to scalar condensation and the hairy black holes constructed here emerge as novel solutions associated to the instability. In the region of phase space where the CLP and hairy black holes coexist, the hairy black holes dominate the microcanonical ensemble and, therefore, describe a new thermodynamic phase of SYM. The hairy black holes extend beyond the CLP extremality surface all the way to the BPS surface, defined by E = 3Q + 2J/L. Through a combination of analytical and numerical techniques, we argue that the BPS limit of the hairy black holes is a singular, horizonless solution, and not a new two-parameter family of BPS black holes that extend the known one-parameter Gutowski-Reall (GR) black hole solution, in contradiction with the conjectures of [1, 2]. To further support our conclusions, we perform a near-horizon analysis of the BPS equations and argue that they do not admit any regular solutions with an horizon. - Open Access
- 25 March 2025
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 134 (12) , 121501
Quantum Mechanics of a Spherically Symmetric Causal Diamond in Minkowski Spacetime
We construct the phase space of a spherically symmetric causal diamond in ( d + 2 )-dimensional Minkowski spacetime. Utilizing the covariant phase space formalism, we identify the relevant degrees of freedom that localize to the d -dimensional bifurcate horizon and, upon canonical quantization, determine their commutators. On this phase space, we find two Iyer-Wald charges. The first of these charges, proportional to the area of the causal diamond, is responsible for shifting the null time along the horizon and has been well documented in the literature. The second charge is much less understood, being integrable for d ≥ 2 only if we allow for field-dependent diffeomorphisms and is responsible for changing the size of the causal diamond.
- 25 March 2025
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 134 (12) , 121501
Open AccessQuantum Mechanics of a Spherically Symmetric Causal Diamond in Minkowski Spacetime
We construct the phase space of a spherically symmetric causal diamond in ( d + 2 )-dimensional Minkowski spacetime. Utilizing the covariant phase space formalism, we identify the relevant degrees of freedom that localize to the d -dimensional bifurcate horizon and, upon canonical quantization, determine their commutators. On this phase space, we find two Iyer-Wald charges. The first of these charges, proportional to the area of the causal diamond, is responsible for shifting the null time along the horizon and has been well documented in the literature. The second charge is much less understood, being integrable for d ≥ 2 only if we allow for field-dependent diffeomorphisms and is responsible for changing the size of the causal diamond.
- Open Access
- 25 November 2024
- Published by American Physical Society (APS) in Physical Review D
- Vol. 110 (10)
Diamond of infrared equivalences in abelian gauge theories
We demonstrate a tree-level equivalence between four distinct infrared objects in ( d + 2 )-dimensional Abelian gauge theories. These are (i) the large gauge charge Q ϵ where the function ϵ on the sphere parametrizing large gauge transformations is identified with the Goldstone mode θ of spontaneously broken large gauge symmetry; (ii) the soft effective action that captures the dynamics of the soft and Goldstone modes; (iii) the edge mode action with Neumann boundary conditions; and (iv) the Wilson line dressing of a scattering amplitude, including a novel dressing for soft photons, which have local charge distributions despite having vanishing global charge. The promotion of the large gauge parameter to the dynamical Goldstone and the novel dressing of soft gauge particles give rise to intriguing possibilities for the future study of infrared dynamics of gauge theories and gravity. Published by the American Physical Society 2024
- 25 November 2024
- Published by American Physical Society (APS) in Physical Review D
- Vol. 110 (10)
Open AccessDiamond of infrared equivalences in abelian gauge theories
We demonstrate a tree-level equivalence between four distinct infrared objects in ( d + 2 )-dimensional Abelian gauge theories. These are (i) the large gauge charge Q ϵ where the function ϵ on the sphere parametrizing large gauge transformations is identified with the Goldstone mode θ of spontaneously broken large gauge symmetry; (ii) the soft effective action that captures the dynamics of the soft and Goldstone modes; (iii) the edge mode action with Neumann boundary conditions; and (iv) the Wilson line dressing of a scattering amplitude, including a novel dressing for soft photons, which have local charge distributions despite having vanishing global charge. The promotion of the large gauge parameter to the dynamical Goldstone and the novel dressing of soft gauge particles give rise to intriguing possibilities for the future study of infrared dynamics of gauge theories and gravity. Published by the American Physical Society 2024
- Open Access
- 24 June 2024
- Published by American Physical Society (APS) in Physical Review D
- Vol. 109 (12) , 125016
On-shell derivation of the soft effective action in Abelian gauge theories
We derive the soft effective action in ()-dimensional Abelian gauge theories from the on-shell action obeying Neumann boundary conditions at timelike and null infinity and Dirichlet boundary conditions at spatial infinity. This allows us to identify the on-shell degrees of freedom on the boundary with the soft modes living on the celestial sphere. Following the work of Donnelly and Wall, this suggests that we can interpret soft modes as entanglement edge modes on the celestial sphere and study entanglement properties of soft modes in Abelian gauge theories.- 24 June 2024
- Published by American Physical Society (APS) in Physical Review D
- Vol. 109 (12) , 125016
Open AccessOn-shell derivation of the soft effective action in Abelian gauge theories
We derive the soft effective action in ()-dimensional Abelian gauge theories from the on-shell action obeying Neumann boundary conditions at timelike and null infinity and Dirichlet boundary conditions at spatial infinity. This allows us to identify the on-shell degrees of freedom on the boundary with the soft modes living on the celestial sphere. Following the work of Donnelly and Wall, this suggests that we can interpret soft modes as entanglement edge modes on the celestial sphere and study entanglement properties of soft modes in Abelian gauge theories. - Open Access
- 30 May 2024
- Published by Stichting SciPost in SciPost Physics
- Vol. 16 (5) , 142
Asymptotic structure of higher dimensional Yang-Mills theory
Using the covariant phase space formalism, we construct the phase space for non-Abelian gauge theories in (d+2)-dimensional Minkowski spacetime for any d ≥ 2, including the edge modes that symplectically pair to the low energy degrees of freedom of the gauge field. Despite the fact that the symplectic form in odd and even-dimensional spacetimes appear ostensibly different, we demonstrate that both cases can be treated in a unified manner by utilizing the shadow transform. Upon quantization, we recover the algebra of the vacuum sector of the Hilbert space and derive a Ward identity that implies the leading soft gluon theorem in (d+2)-dimensional spacetime.
- 30 May 2024
- Published by Stichting SciPost in SciPost Physics
- Vol. 16 (5) , 142
Open AccessAsymptotic structure of higher dimensional Yang-Mills theory
Using the covariant phase space formalism, we construct the phase space for non-Abelian gauge theories in (d+2)-dimensional Minkowski spacetime for any d ≥ 2, including the edge modes that symplectically pair to the low energy degrees of freedom of the gauge field. Despite the fact that the symplectic form in odd and even-dimensional spacetimes appear ostensibly different, we demonstrate that both cases can be treated in a unified manner by utilizing the shadow transform. Upon quantization, we recover the algebra of the vacuum sector of the Hilbert space and derive a Ward identity that implies the leading soft gluon theorem in (d+2)-dimensional spacetime.
- Open Access
- 7 November 2023
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2023 (11) , 1-75
Phase space renormalization and finite BMS charges in six dimensions
We perform a complete and systematic analysis of the solution space of six-dimensional Einstein gravity. We show that a particular subclass of solutions — those that are analytic near $$ \mathcal{I} $$ + — admit a non-trivial action of the generalised Bondi-Metzner-van der Burg-Sachs (GBMS) group which contains infinite-dimensional supertranslations and superrotations. The latter consists of all smooth volume-preserving Diff×Weyl transformations of the celestial S4. Using the covariant phase space formalism and a new technique which we develop in this paper (phase space renormalization), we are able to renormalize the symplectic potential using counterterms which are local and covariant. The Hamiltonian charges corresponding to GBMS diffeomorphisms are non-integrable. We show that the integrable part of these charges faithfully represent the GBMS algebra and in doing so, settle a long-standing open question regarding the existence of infinite-dimensional asymptotic symmetries in higher even dimensional non-linear gravity. Finally, we show that the semi-classical Ward identities for supertranslations and superrotations are precisely the leading and subleading soft-graviton theorems respectively.- 7 November 2023
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2023 (11) , 1-75
Open AccessPhase space renormalization and finite BMS charges in six dimensions
We perform a complete and systematic analysis of the solution space of six-dimensional Einstein gravity. We show that a particular subclass of solutions — those that are analytic near $$ \mathcal{I} $$ + — admit a non-trivial action of the generalised Bondi-Metzner-van der Burg-Sachs (GBMS) group which contains infinite-dimensional supertranslations and superrotations. The latter consists of all smooth volume-preserving Diff×Weyl transformations of the celestial S4. Using the covariant phase space formalism and a new technique which we develop in this paper (phase space renormalization), we are able to renormalize the symplectic potential using counterterms which are local and covariant. The Hamiltonian charges corresponding to GBMS diffeomorphisms are non-integrable. We show that the integrable part of these charges faithfully represent the GBMS algebra and in doing so, settle a long-standing open question regarding the existence of infinite-dimensional asymptotic symmetries in higher even dimensional non-linear gravity. Finally, we show that the semi-classical Ward identities for supertranslations and superrotations are precisely the leading and subleading soft-graviton theorems respectively. - Open Access
Asymptotic Symmetries and Weinberg's Soft Photon Theorem in Mink$_{d+2}$
We show that Weinberg's leading soft photon theorem in massless abelian gauge theories implies the existence of an infinite-dimensional large gauge symmetry which acts non-trivially on the null boundaries ${\mathscr I}^\pm$ of $(d+2)$-dimensional Minkowski spacetime. These symmetries are parameterized by an arbitrary function $\varepsilon(x)$ of the $d$-dimensional celestial sphere living at ${\mathscr I}^\pm$. This extends the previously established equivalence between Weinberg's leading soft theorem and asymptotic symmetries from four and higher even dimensions to \emph{all} higher dimensions.Open AccessAsymptotic Symmetries and Weinberg's Soft Photon Theorem in Mink$_{d+2}$
We show that Weinberg's leading soft photon theorem in massless abelian gauge theories implies the existence of an infinite-dimensional large gauge symmetry which acts non-trivially on the null boundaries ${\mathscr I}^\pm$ of $(d+2)$-dimensional Minkowski spacetime. These symmetries are parameterized by an arbitrary function $\varepsilon(x)$ of the $d$-dimensional celestial sphere living at ${\mathscr I}^\pm$. This extends the previously established equivalence between Weinberg's leading soft theorem and asymptotic symmetries from four and higher even dimensions to \emph{all} higher dimensions. - Open Access
- 8 May 2023
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2023 (5) , 1-105
New phases of $ \mathcal{N} $ = 4 SYM at finite chemical potentialWe do a systematic search of supergravity solutions that, via the AdS5/CFT4correspondence, are dual to thermal states in $$ \mathcal{N} $$ = 4 SYM at finite chemical potential. These solutions dominate the microcanonical ensemble and are required to ultimately reproduce the microscopic entropy of AdS black holes. Using a mix of analytical and numerical methods, we construct and study static charged hairy solitonic and black hole solutions with global AdS5asymptotics. They are constructed in two distinct consistent truncations of five dimensional gauged supergravity (and can thus be uplifted to asymptotically AdS5×S5solutions of type IIB supergravity). In the “single charge” truncation which consists of one charged scalar field, hairy black holes exist above a critical charge and merge with the known Behrndt-Cvetič-Sabra (BCS) black holes along a curve determined by the onset of superradiance in the latter family. The lowest mass hairy black hole is a singular zero entropy soliton. In the “two charge” truncation which consists of a two equal charged scalar fields, hairy black holes exist for all charges and merge with the known BCS black holes along their superradiant onset curve. The lowest mass hairy black hole is a smooth supersymmetric zero entropy soliton. Together with the known phases of the truncation with three equal charges, our findings permit a good understanding of the full phase space of SYM thermal states with three arbitrary chemical potentials.- 8 May 2023
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2023 (5) , 1-105
Open AccessNew phases of $ \mathcal{N} $ = 4 SYM at finite chemical potentialWe do a systematic search of supergravity solutions that, via the AdS5/CFT4correspondence, are dual to thermal states in $$ \mathcal{N} $$ = 4 SYM at finite chemical potential. These solutions dominate the microcanonical ensemble and are required to ultimately reproduce the microscopic entropy of AdS black holes. Using a mix of analytical and numerical methods, we construct and study static charged hairy solitonic and black hole solutions with global AdS5asymptotics. They are constructed in two distinct consistent truncations of five dimensional gauged supergravity (and can thus be uplifted to asymptotically AdS5×S5solutions of type IIB supergravity). In the “single charge” truncation which consists of one charged scalar field, hairy black holes exist above a critical charge and merge with the known Behrndt-Cvetič-Sabra (BCS) black holes along a curve determined by the onset of superradiance in the latter family. The lowest mass hairy black hole is a singular zero entropy soliton. In the “two charge” truncation which consists of a two equal charged scalar fields, hairy black holes exist for all charges and merge with the known BCS black holes along their superradiant onset curve. The lowest mass hairy black hole is a smooth supersymmetric zero entropy soliton. Together with the known phases of the truncation with three equal charges, our findings permit a good understanding of the full phase space of SYM thermal states with three arbitrary chemical potentials. - Open Access
- 7 January 2022
- Published by American Physical Society (APS) in Physical Review D
- Vol. 105 (2) , 026009
Shadows and soft exchange in celestial CFT
We study exponentiated soft exchange in ()-dimensional gauge and gravitational theories using the celestial conformal field theory formalism. These models exhibit spontaneously broken asymptotic symmetries generated by gauge transformations with noncompact support, and the effective dynamics of the associated Goldstone “edge” mode is expected to be -dimensional. The introduction of an infrared regulator also explicitly breaks these symmetries so the edge mode in the regulated theory is really a -dimensional pseudo-Goldstone boson. Symmetry considerations determine the leading terms in the effective action, whose coefficients are controlled by the infrared cutoff. Computations in this model reproduce the Abelian infrared divergences in and capture the resummed (infrared finite) soft exchange in higher dimensions. The model also reproduces the leading soft theorems in gauge and gravitational theories in all dimensions. Interestingly, we find that it is the shadow transform of the Goldstone mode that has local -dimensional dynamics: the effective action expressed in terms of the Goldstone mode is nonlocal for . We also introduce and discuss new magnetic soft theorems. Our analysis demonstrates that symmetry principles suffice to calculate soft exchange in gauge theory and gravity.- 7 January 2022
- Published by American Physical Society (APS) in Physical Review D
- Vol. 105 (2) , 026009
Open AccessShadows and soft exchange in celestial CFT
We study exponentiated soft exchange in ()-dimensional gauge and gravitational theories using the celestial conformal field theory formalism. These models exhibit spontaneously broken asymptotic symmetries generated by gauge transformations with noncompact support, and the effective dynamics of the associated Goldstone “edge” mode is expected to be -dimensional. The introduction of an infrared regulator also explicitly breaks these symmetries so the edge mode in the regulated theory is really a -dimensional pseudo-Goldstone boson. Symmetry considerations determine the leading terms in the effective action, whose coefficients are controlled by the infrared cutoff. Computations in this model reproduce the Abelian infrared divergences in and capture the resummed (infrared finite) soft exchange in higher dimensions. The model also reproduces the leading soft theorems in gauge and gravitational theories in all dimensions. Interestingly, we find that it is the shadow transform of the Goldstone mode that has local -dimensional dynamics: the effective action expressed in terms of the Goldstone mode is nonlocal for . We also introduce and discuss new magnetic soft theorems. Our analysis demonstrates that symmetry principles suffice to calculate soft exchange in gauge theory and gravity. - Open Access
- 11 August 2021
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2021 (8) , 1-31
Infinite-dimensional fermionic symmetry in supersymmetric gauge theories
We establish the existence of an infinite-dimensional fermionic symmetry in four-dimensional supersymmetric gauge theories by analyzing semiclassical photino dynamics in abelian $$ \mathcal{N} $$ = 1 theories with charged matter. The symmetry is parametrized by a spinor-valued function on an asymptotic S2 at null infinity. It is not manifest at the level of the Lagrangian, but acts non-trivially on physical states, and its Ward identity is the soft photino theorem. The infinite-dimensional fermionic symmetry resides in the same $$ \mathcal{N} $$ = 1 supermultiplet as the physically non-trivial large gauge symmetries associated with the soft photon theorem.- 11 August 2021
- Published by Springer Nature in Journal of High Energy Physics
- Vol. 2021 (8) , 1-31
Open AccessInfinite-dimensional fermionic symmetry in supersymmetric gauge theories
We establish the existence of an infinite-dimensional fermionic symmetry in four-dimensional supersymmetric gauge theories by analyzing semiclassical photino dynamics in abelian $$ \mathcal{N} $$ = 1 theories with charged matter. The symmetry is parametrized by a spinor-valued function on an asymptotic S2 at null infinity. It is not manifest at the level of the Lagrangian, but acts non-trivially on physical states, and its Ward identity is the soft photino theorem. The infinite-dimensional fermionic symmetry resides in the same $$ \mathcal{N} $$ = 1 supermultiplet as the physically non-trivial large gauge symmetries associated with the soft photon theorem.