Particle creation in nonstationary large N quantum mechanics
Abstract
We consider an analog of particle production in a quartic O (N ) quantum oscillator with timedependent frequency, which is a toy model of particle production in the dynamical Casimir effect and de Sitter space. We calculate exact quantum averages, Keldysh propagator, and particle number using two different methods. First, we employ a kind of rotating wave approximation to estimate these quantities for small deviations from stationarity. Second, we extend these results to arbitrarily large deviations using the SchwingerKeldysh diagrammatic technique. We show that in strongly nonstationary situations, including resonant oscillations, loop corrections to the treelevel expressions effectively result in an additional degree of freedom, N →N +3/2 , which modifies the average number and energy of created particles.
 Publication:

Physical Review D
 Pub Date:
 August 2021
 DOI:
 10.1103/PhysRevD.104.045001
 arXiv:
 arXiv:2105.01647
 Bibcode:
 2021PhRvD.104d5001T
 Keywords:

 High Energy Physics  Theory;
 General Relativity and Quantum Cosmology;
 Quantum Physics
 EPrint:
 14 pages + appendices, 4 figures. v4: minor corrections in section 4