Casimir effect in critical O(N) models from nonequilibrium Monte Carlo simulations.

Bulgarelli, Andrea; Caselle, Michele; Nada, Alessandro; Panero, Marco · Phys Rev E · 2025

basic_science · Level V

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Abstract

O(N) vector models in three dimensions, when defined in a geometry with a compact direction and tuned to criticality, exhibit long-range fluctuations which induce a Casimir effect. The strength of the resulting interaction is encoded in the excess free-energy density, which depends on a universal coefficient: the Casimir amplitude. We present a high-precision numerical calculation of the latter by means of a nonequilibrium Monte Carlo algorithm and compare our findings with results obtained from large-N expansions and from the conformal bootstrap.