arXiv subjects

Shivam K. Sharma

Publications and source records attributed to Shivam K. Sharma.

4 recordsLinked to original sources

arXiv2026

Loops Outside a Black Hole

We present a general conjecture for evaluating multiple discontinuity integrals arising from bulk loop diagrams in the gravitational Schwinger-Keldysh geometry. This generalises earlier tree-level results in arXiv:2403.10654 to arbitrary bulk loops with no tadpoles (for scalar non-derivative interactions). The conjectured result takes the form of loop integrals performed in a real-time finite-temperature field theory living on the exterior of the black hole. We check our conjecture against all one-loop and many two and three-loop contributions to two, three, and four-point functions. Our diagrammatic rules for the exterior field theory are consistent with microscopic unitarity and thermality at arbitrary loop level. We also remark on a novel approach to real-time finite-temperature holography based on bulk Schwinger-Dyson equations, with the vertices integrated over the black hole exterior.

hep-th↗

arXiv2025

Holographic Fluctuation-Dissipation Relations in Finite Density Systems

Using real-time holography, we investigate fluctuation-dissipation relations in holographic systems at finite density. In the bulk, it corresponds to the study of scattering of a charged scalar field against a charged black hole background, leading to an exterior field theory outside the AdS Reissner-Nordström black hole. This theory captures dissipation (from infalling Quasi-normal modes) and fluctuations (from Hawking radiation). Here, we also develop a Witten diagrammatic framework for computing $n$-point functions for interacting charged scalars. From the boundary perspective, it gives real-time correlations of the dual CFT held at finite temperature and finite chemical potential. Our results yield (non)-linear holographic fluctuation-dissipation relations at small but finite density, which are shown to recover the correct behaviour in the zero-density limit.

hep-th↗

arXiv2025

Open EFT for Interacting Fermions from Holography

We initiate the study of an open EFT for finite-temperature holographic systems with interacting fermions. In particular, we do this for Yukawa interactions in the bulk using the real-time formalism (grSK geometry). From the bulk perspective, this study corresponds to Yukawa scattering against a black hole, incorporating the effects of Hawking radiation. We derive an EFT in the exterior of the black hole and thus develop a Witten diagrammatic understanding of the scattering processes. This allows the explicit evaluation of boundary Schwinger-Keldysh (SK) correlators to arbitrary order, at tree-level in the bulk. Here we present explicitly the SK generating functional up to four-point functions. Finally, we represent the correlators in a column-vector representation that manifests microscopic unitarity and thermality, with all the statistical factors neatly folded in.

hep-th↗

arXiv2020

Holographic KMS relations at finite density

We extend the holographic Schwinger-Keldysh prescription introduced in arXiv:1812.08785 to charged black branes, with a view towards studying Hawking radiation in these backgrounds. Equivalently we study real-time fluctuations of the dual CFT held at finite temperature and finite chemical potential. We check our prescription using charged Dirac probe fields. We solve the Dirac equation in a boundary derivative expansion extending the results in arXiv:2011.07039. The Schwinger-Keldysh correlators derived using this prescription automatically satisfy the appropriate KMS relations with Fermi-Dirac factors.

hep-th↗