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Main Authors: Fernández-Sarmiento, Lucas, Penco, Riccardo, Rosen, Rachel A
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.14978
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author Fernández-Sarmiento, Lucas
Penco, Riccardo
Rosen, Rachel A
author_facet Fernández-Sarmiento, Lucas
Penco, Riccardo
Rosen, Rachel A
contents Consistency constraints for low-energy theories, especially those lacking Lorentz invariance, have recently garnered attention. Building on results from black hole thermodynamics, we investigate the conjecture that leading symmetry-preserving irrelevant deformations of a conformal field theory (CFT) in the infrared must increase the system's entropy. We show that this entropy-positivity conjecture is equivalent to a decrease in the thermal grand potential at a fixed temperature. We then evaluate this proposal against various known positivity bounds and other physical constraints on effective theories: for $U(1)$ Goldstone bosons with a quartic self-interaction at (non-)zero chemical potential, for the Euler-Heisenberg model, for the $O(N)$ nonlinear sigma model in $(2+1)D$, and for $T\bar{T}$ deformations of the 2D Ising CFT. We find broad agreement with the entropy-positivity conjecture, and we discuss test cases where the conjecture is not expected to apply, such as deformations that break internal symmetries of the CFT.
format Preprint
id arxiv_https___arxiv_org_abs_2508_14978
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle On Entropy Bounds for Irrelevant Operators
Fernández-Sarmiento, Lucas
Penco, Riccardo
Rosen, Rachel A
High Energy Physics - Theory
Consistency constraints for low-energy theories, especially those lacking Lorentz invariance, have recently garnered attention. Building on results from black hole thermodynamics, we investigate the conjecture that leading symmetry-preserving irrelevant deformations of a conformal field theory (CFT) in the infrared must increase the system's entropy. We show that this entropy-positivity conjecture is equivalent to a decrease in the thermal grand potential at a fixed temperature. We then evaluate this proposal against various known positivity bounds and other physical constraints on effective theories: for $U(1)$ Goldstone bosons with a quartic self-interaction at (non-)zero chemical potential, for the Euler-Heisenberg model, for the $O(N)$ nonlinear sigma model in $(2+1)D$, and for $T\bar{T}$ deformations of the 2D Ising CFT. We find broad agreement with the entropy-positivity conjecture, and we discuss test cases where the conjecture is not expected to apply, such as deformations that break internal symmetries of the CFT.
title On Entropy Bounds for Irrelevant Operators
topic High Energy Physics - Theory
url https://arxiv.org/abs/2508.14978