arXiv subjects

Emilie Despontin

Publications and source records attributed to Emilie Despontin.

4 recordsLinked to original sources

arXiv2026

Quantum corrections to the near-extremal thermodynamics of (warped) BTZ black holes

We study one-loop effects in the near-extremal thermodynamics of BTZ and warped BTZ black holes, with particular emphasis on the fate of eigenmodes that become zero modes in the extremal throat. Our analysis is formulated in three-dimensional Topologically Massive Gravity, a higher derivative theory characterized by the presence of a gravitational Chern--Simons term, and it makes use of the Newman--Penrose formulation. For BTZ, we compare the near-horizon computation with the full-geometry eigenvalue problem and identify how the Schwarzian and rotational sectors are lifted at small temperature. We then extend the same strategy to warped BTZ. We find that rotational modes are essential for a consistent near-extremal treatment of both BTZ and warped BTZ black holes, and cannot be discarded without first specifying the boundary conditions.

hep-th↗

arXiv2025

Infinite-dimensional symmetries in plane wave spacetimes

We study the asymptotic symmetries of the Nappi-Witten spacetime in four dimensions, a plane wave arising as the Penrose limit of AdS$_2\times S^2$. Imposing suitable boundary conditions at large transverse distance, we uncover a new infinite-dimensional symmetry algebra allowing for non-trivial central extensions. The corresponding phase space encompasses the most general four-dimensional pp-wave metric, including in particular the Penrose limit of Kerr black holes.

hep-th↗

arXiv2025

Anisotropic conformal Carroll field theories and their gravity duals

We investigate anisotropic conformal Carroll field theories and their holographic duals. On the field theory side, we focus on the case with scaling exponent $z=0$ in two and three spacetime dimensions. These theories exhibit infinite-dimensional symmetry algebras, including supertranslations and superrotations, and are closely related to, but distinct from, Warped Conformal Field Theories. We construct the associated Carrollian stress tensor, derive its transformation properties, and analyse the structure of correlation functions under different choices of vacua. On the gravity side, we identify three and four-dimensional plane wave geometries whose isometry algebras realise the two- and three-dimensional Carroll algebra and anisotropic scale transformations. We propose, for each scaling exponent, a phase space of asymptotically-plane wave spacetimes and show that the residual diffeomorphisms reproduce the expected conformal Carroll field theory algebra, establishing a framework for anisotropic Carrollian holography.

hep-th↗

arXiv2024

Were you born in an aborted primordial black hole?

We propose a mechanism of electroweak baryogenesis based on the Standard Model and explaining the coincidence between the baryon and Dark Matter (DM) densities. Large curvature fluctuations slightly below the threshold for Primordial Black Hole (PBH) formation locally reheat the plasma above the sphaleron barrier when they collapse gravitationally, leading to regions with a maximal baryogenesis at the Quantum Chromodynamics epoch. Using numerical relativity simulations, we calculate the overdensity threshold for baryogenesis. If PBH significantly contribute to the DM, aborted PBHs can generate a baryon density and an averaged baryon-to-photon ratio consistent with observations.

astro-ph.CO↗