SPSounak Pal

Sounak Pal

*This is an algorithmically generated author record based on publicly available information.

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Sounak Pal has a total of 14 co-authors. Here are the top co-authors by number of shared publications:


Latest Publications

  • Open Access

    On the resolution of categorical symmetries in (non-) unitary rational CFTs

    by Arpan Bhattacharyya, Saptaswa Ghosh, Sounak Pal, Jagannath Santara

    We explore several aspects of categorical symmetry-resolved entanglement entropy (SREE) directly within two-dimensional rational conformal field theory (RCFT) (without invoking any SymTFT construction [Y. Choi et al., Phys. Rev. Lett. 133, 251602 (2024)]). We derive a general formula applicable whenever the action of the relevant topological defect lines on the annulus Hilbert space is known. This framework accommodates weakly and strongly symmetric boundaries, cloaking states, and fusion rings with multiplicities. We verify the formula in a range of diagonal unitary and non-unitary examples, including theories with generalized Haagerup-Izumi modular data. Furthermore, we extend the analysis to non-diagonal RCFTs. The \frac{1}{2}E_6 1 2 E 6 example demonstrates that closed-channel modular data and NIM-rep multiplicities alone do not suffice to determine the defect action on the complete open-channel Hilbert space.

  • Open Access

    Heterotic footprints in classical gravity: PM dynamics from on-shell soft amplitudes at one loop

    by Arpan Bhattacharyya, Saptaswa Ghosh, Ankit Mishra, Sounak Pal

    A bstract: We study classical scattering of charged black holes in Einstein-Maxwell-Dilaton (EMD) theory. Working in the classical (Post-Minkowskian) regime, we extract the conservative two-body potential by expanding the one-loop amplitudes in the soft regime. We explicitly show that, as in GR, the relevant soft amplitudes are infrared (IR) finite when long-range interactions are consistently treated via the Lippmann-Schwinger equation and the associated IR subtraction. The scattering angle is then obtained from the eikonal exponentiation of the soft amplitude. Our results track the separate roles of electromagnetic and dilatonic charges in both the conservative dynamics and the eikonal phase, and they smoothly reduce to the GR limit when the charges and the dilaton coupling are switched off. Where applicable, we compare our results with existing literature and find agreement. These findings provide amplitude-based benchmarks for compact-object dynamics in EMD and furnish building blocks for waveform modeling in beyond-GR scenarios.


  • Open Access

    Finite cutoff JT gravity: Baby universes, matrix dual, and (Krylov) complexity

    by Arpan Bhattacharyya, Saptaswa Ghosh, Sounak Pal, Anandu Vinod

    In this paper, as an application of the ‘Complexity = Volume’ proposal, we calculate the growth of the interior of a black hole at late times for finite cutoff JT gravity. Due to this integrable, irrelevant deformation, the spectral properties are modified non-trivially. The Einstein-Rosen Bridge (ERB) length saturates faster than pure JT gravity. We comment on the possible connection between Krylov Complexity and ERB length for the deformed theory. Apart from this, we compute the emission probability of baby universes in the deformed theory and find that it changes due to the deformation parameter only if we turn on Lorentzian evolution. We also find that the saturation time of the deformed theory relative to the undeformed one depends on the inverse temperature. We also highlight the subtleties involved in the dual matrix model and comment on the possible one-cut universality. Finally, we comment on the possible correction to the volume of the moduli space arising from the non-perturbative correction of the spectral curve induced by the finite boundary cutoff.


  • Open Access

    Love beyond Einstein: metric reconstruction and Love number in quadratic gravity using WEFT

    by Arpan Bhattacharyya, Saptaswa Ghosh, Naman Kumar, Shailesh Kumar, Sounak Pal

    A bstract: We study tidal Love numbers of static black holes in four-dimensional quadratic theory of gravity, extending the result of GR. We use worldline effective field theory (WEFT) methods to compute metric perturbations from one-point functions, treating the higher-derivative terms perturbatively. We show that insertions of scalar fields on the worldline induce non-zero tidal tails, and the corresponding Love number displays no RG running. The same conclusion holds for the insertions of tensor fields. Furthermore, for scalar dipole perturbations, we derive a Yukawa-deformed Frobenius solution and match the asymptotic behavior to fix the UV charge, finding agreement with EFT predictions of Wilson coefficients. Our work demonstrates that quadratic higher-curvature corrections induce non-zero but scale-independent tidal responses, offering a robust EFT framework to test deviations from GR in gravitational wave observations.


  • Open Access

    The sky remembers everything: Celestial amplitude, shadow and OPE in quadratic EFT of gravity

    by Arpan Bhattacharyya, Saptaswa Ghosh, Sounak Pal

    In this paper, we compute the celestial amplitude arising from higher curvature corrections to Einstein gravity, incorporating phase dressing. The inclusion of such corrections leads to effective modifications of the theory’s ultraviolet (UV) behaviour. In the eikonal limit, we find that, in contrast to Einstein’s gravity, where the u u and s s -channel contributions cancel, these contributions remain non-vanishing in the presence of higher curvature terms. We examine the analytic structure of the resulting amplitude and derive a dispersion relation for the phase-dressed eikonal amplitude in quadratic gravity. Furthermore, we investigate the celestial conformal block expansion of the Mellin-transformed conformal shadow amplitude within the framework of celestial conformal field theory (CCFT). As a consequence, we compute the corresponding operator product expansion (OPE) coefficients using the Burchnall-Chaundy expansion. In addition, we evaluate the OPE via the Euclidean OPE inversion formula across various kinematic channels and comment on its applicability and implications. Finally, we briefly explore the Carrollian amplitude associated with the corresponding quadratic EFT.


  • Open Access

    Bootstrapping the spinning two body problem in dynamical Chern-Simons gravity using worldline QFT

    by Arpan Bhattacharyya, Debodirna Ghosh, Saptaswa Ghosh, Sounak Pal

    In this paper, we compute the WQFT partition function, specifically the eikonal phase in a black hole scattering event in the dynamical Chern-Simons theory, using the techniques of spinning worldline quantum field theory. We consider the scattering of spinning black holes and highlight the necessary details for the calculation of the partition function. We present the ϵ-expansion of the essential two-loop integrals using Integration-by-Parts (IBP) reduction and differential equation techniques, which we then utilize to compute the linear-in-order spin eikonal phase up to 3PM. Additionally, we discuss the dependence of the phase on the spin orientations of the black holes.


  • Open Access

    3D $ \mathcal{N} $ = 1 supergravity from Virasoro TQFT: gravitational partition function and Out-of-time-order correlator

    by Arpan Bhattacharyya, Saptaswa Ghosh, Poulami Nandi, Sounak Pal

    In this paper, we compute the partition functions of $$ \mathcal{N} $$ N = 1 SUGRA for different boundary topologies, i.e. punctured sphere and torus, using super-Virasoro TQFT. We use fusion and modular kernels of the super-Liouville theory to compute the necklace-channel conformal block and showcase formalism by proving that the inner product holds for superconformal blocks, defined as states in the Hilbert space. Finally, we compute the out-of-time-order correlator for the torus topology with superconformal primary insertions as matter using the tools of super-Virasoro TQFT and investigate its early-time behaviour.


  • Open Access

    Aspects of TT¯+JT¯ deformed Schwarzian: From gravity partition function to late-time spectral form factor

    by Arpan Bhattacharyya, Saptaswa Ghosh, Sounak Pal

    In this paper, we investigate different thermodynamic properties of T T ¯ + J T ¯ deformed Schwarzian theory and its different gravitational perspectives. First, we compute the partition function of U ( 1 ) coupled 2D-gravity with fixed chemical potential, obtained from the dimensional reduction of the four-dimensional Einstein-Maxwell theory. Then, we compute the partition function of the gravity theory which is the dual to the deformed Schwarzian living on its boundary and study the genus expansion of the one and two-point correlation function of the partition function of the theory. Subsequently, we use the one-point function to compute the “annealed” and “quenched” free energy in low-temperature limits and make a qualitative comparison with the undeformed theory. Then, using the two-point function, we compute the spectral form factor of the deformed theory in early and late time. We find a dip and ramp structure in early and late time, respectively. We also get a plateau structure in the τ -scaling limit. Last but not least, we comment on the late-time topology change to give a physical interpretation of the ramp of the spectral form factor for our theory. Published by the American Physical Society 2024


  • Open Access

    Observables from classical black hole scattering in Scalar-Tensor theory of gravity from worldline quantum field theory

    by Arpan Bhattacharyya, Debodirna Ghosh, Saptaswa Ghosh, Sounak Pal

    In this article, we compute the two observables, impulse and waveform, in a black hole scattering event for the Scalar-Tensor theory of gravity with a generic scalar potential using the techniques of Worldline Quantum Field Theory. We mainly investigate the corrections to the above mentioned observables due to the extra scalar degree of freedom. For the computation of impulse, we consider the most general scenario by making the scalar field massive and then show that each computed diagram has a smooth massless limit. We compute the waveform for scalar and graviton up to 2PM, taking the scalar as massless. Furthermore, we discuss if the scalar has mass and how the radiation integrals get more involved than the massless case. We also arrive at some analytical results using stationary phase approximation.

  • Open Access

    Observables from classical black hole scattering in Scalar-Tensor theory of gravity from worldline quantum field theory

    by Arpan Bhattacharyya, Debodirna Ghosh, Saptaswa Ghosh, Sounak Pal

    In this paper, we compute the two observables, impulse and waveform, in a black hole scattering event for the Scalar-Tensor theory of gravity with a generic scalar potential using the techniques of Worldline Quantum Field Theory. We mainly investigate the corrections to the above mentioned observables due to the extra scalar degree of freedom. For the computation of impulse, we consider the most general scenario by making the scalar field massive and then show that each computed diagram has a smooth massless limit. We compute the waveform for scalar and graviton up to 2PM, taking the scalar as massless. Furthermore, we discuss if the scalar has mass and how the radiation integrals get more involved than the massless case. We also arrive at some analytical results using stationary phase approximation. Interestingly, we also show that the λ 4 φ 4 interaction vertex does not contribute to the radiation by showing that the integral has no non-zero finite value.