arXiv subjects

Diego Pardo Santos

Publications and source records attributed to Diego Pardo Santos.

4 recordsLinked to original sources

arXiv2025

Mass and entropy of asymptotically flat eternal quantum black holes in 2D

Semi-classical dilaton gravity in (1+1)-dimensions remains one of the only arenas where quantum black holes can be exactly constructed, fully accounting for backreaction due to quantum matter. Here we provide a comprehensive analysis of the mass and thermodynamic properties of static asymptotically flat quantum black holes both analytically and numerically. First, we analytically investigate eternal quantum black hole solutions to a one-parameter family of analytically solvable models interpolating between Russo-Susskind-Thorlacius and Bose, Parker, and Peleg gravities. Examining these models in a semi-classically allowed parameter space, we find naked singularities may exist for quantum fields in the Boulware state. Using a quasi-local formalism, where we confine the black hole to a finite sized cavity, we derive the conserved energy and analyze the system's thermal behavior. Specifically, we show the semi-classical Wald entropy precisely equals the generalized entropy, accounting for both gravitational and fine grained matter entropies, and we find a range where the quantum black holes are thermally stable. Finally, we numerically construct eternal black hole solutions to semi-classical Callan-Giddings-Harvey-Strominger gravity and find their thermal behavior is qualitatively different from their analytic counterparts. In the process, we develop an analytic expansion of the solutions and find it accurately approximates the full numerical solutions in the semi-classical limit.

gr-qc↗

arXiv2025

Mapping 1+1-dimensional black hole thermodynamics to finite volume effects

Both black hole thermodynamics and finite volume effects in quantum field theory violate the null energy condition. Motivated by this, we compare thermodynamic features between two $1+1$-dimensional systems: (i) a scalar field confined to a periodic spatial interval of length $a$ and tunneling between two degenerate vacua; (ii) a dilatonic black hole at temperature $T$ in the presence of matter fields. If we identify $a\propto T^{-1}$, we find similar thermodynamic behaviour, which suggests some deeper connection arising from the presence of non-trivial boundary conditions in both systems. We then extend our results to $2+1$ and $3+1$-dimensions and, although a more complete study is necessary, the connection found in $1+1$-dimensions seems to be valid in higher dimensions too.

hep-th↗

arXiv2024

How negative can null energy be in large N CFTs?

Smeared null energy has been shown to be bounded from below for free minimally coupled quantum field theories. This is not the case for conformally coupled free bosonic theories where states of unbounded null energy can be constructed by increasing the particle number. Little is known for interacting conformal field theories (CFTs) in dimensions larger than two. In this work we consider states that are superpositions of scalar primary operators or the stress-energy tensor itself in large N CFTs. Within the large N approximation we present arguments that the negative smeared null energy of such states scales at worst as the central charge of theory, $C_T$. This provides evidence for a general bound for CFTs in d-dimensions proportional to the central charge.

hep-th↗

arXiv2023

Non-minimal coupling, negative null energy, and effective field theory

The non-minimal coupling of scalar fields to gravity has been claimed to violate energy conditions, leading to exotic phenomena such as traversable wormholes, even in classical theories. In this work we adopt the view that the non-minimal coupling can be viewed as part of an effective field theory (EFT) in which the field value is controlled by the theory's cutoff. Under this assumption, the average null energy condition, whose violation is necessary to allow traversable wormholes, is obeyed both classically and in the context of quantum field theory. In addition, we establish a type of "smeared" null energy condition in the non-minimally coupled theory, showing that the null energy averaged over a region of spacetime obeys a state dependent bound, in that it depends on the allowed field range. We finally motivate our EFT assumption by considering when the gravity plus matter path integral remains semi-classically controlled.

hep-th↗