Semiclassical backreaction : a qualitative assessment
van Dissel, Fabio (Institut de Física d'Altes Energies)
Zahariade, George (Uniwersytet Jagielloński)

Date:	2025
Abstract:	The backreaction of quantum degrees of freedom on classical backgrounds is a poorly understood topic in theoretical physics. Most often it is treated within the semiclassical approximation with the help of various ad hoc prescriptions accounting for the effect of quantum excitations on the dynamics of the background. We focus on two popular ones: (i) the mean-field approximation whereby quantum degrees of freedom couple to the classical background via their quantum expectation values; (ii) the (stochastic) truncated Wigner method whereby the fully coupled system is evolved using classical equations of motion for various randomly sampled initial conditions of the quantum degree of freedom, and a statistical average is performed a posteriori. We evaluate the performance of each method in a simple toy model against a fully quantum mechanical treatment, and identify its regime of validity. We interpret the results in terms of quantum entanglement and loss of classicality of the background.
Grants:	Agència de Gestió d'Ajuts Universitaris i de Recerca 2021/SGR-00649 Ministerio de Ciencia e Innovación PRE2020-094420
Rights:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Language:	Anglès
Document:	Article ; recerca ; Versió publicada
Subject:	Classical solutions in field theory ; Cosmology ; Quantum field theory ; Quantum fields in curved spacetime ; Semiclassical physics
Published in:	Physical Review D, Vol. 111, Issue 6 (March 2025) , art. 065008, ISSN 2470-0029

DOI: 10.1103/PhysRevD.111.065008

20 p, 3.1 MB

The record appears in these collections:
Research literature > UAB research groups literature > Research Centres and Groups (research output) > Experimental sciences > Institut de Física d’Altes Energies (IFAE)
Articles > Research articles
Articles > Published articles