Mickael Komendyak | Searcharxiv

arXiv2026

Ramp and plateau in bulk correlators within the disk topology in JT gravity

We study bulk two-point correlation functions of a massless scalar field in Jackiw-Teitelboim gravity around the eternal black hole saddle. While same-side correlators exhibit exponential decay, two sided correlators, at the next to leading order in steepest descent approximation, exhibit a ramp followed by a plateau after the initial semiclassical exponential decay. Our results indicate that the late-time saturation of two-sided correlators is already visible within the perturbative saddle expansion of the bulk path integral, without invoking nonperturbative e^{-S} effects. Finally, we show that the dip-time, defined as the minimum of the correlator, grows inversely with the black hole temperature, consistent with expectations from the holographic dual.

hep-th↗

arXiv2024

A novel approach to cosmological particle production

In this work we present a novel approach to the study of cosmological particle production in asymptotically Minkowski spacetimes. We emphasize that it is possible to determine the amount of particle production by focusing on the mathematical properties of the mode function equations,i.e. their singularities and monodromies, sidestepping the need to solve those equations. We consider in detail creation of scalar and spin 1/2 particles in four dimensional asymptotically Minkowski flat FLRW spacetimes. We explain that when the mode function equation for scalar fields has only regular singular points, the corresponding scale factors are asymptotically Minkowski. For Dirac spin 1/2 fields, the requirement of mode function equations with only regular points is more restrictive, and picks up a subset of the aforementioned scale factors. For the scalar case, we argue that there are two different regimes of particle production; while most of the literature has focused on only one of these regimes, the other regime presents enhanced particle production. On the other hand, for Dirac fermions we find a single regime of particle production. Finally, we very briefly comment on the possibility of studying particle production in spacetimes that don't asymptote to Minkowski, by considering mode function equations with irregular singular points.

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