Non-equilibrium dynamics of a scalar field with quantum backreaction
Kainulainen, K., & Koskivaara, O. (2021). Non-equilibrium dynamics of a scalar field with quantum backreaction. Journal of High Energy Physics, 2021(12), Article 190. https://doi.org/10.1007/jhep12(2021)190
Published inJournal of High Energy Physics
© The Authors. Article funded by SCOAP3
We study the dynamical evolution of coupled one- and two-point functions of a scalar field in the 2PI framework at the Hartree approximation, including backreaction from out-of-equilibrium modes. We renormalize the 2PI equations of motion in an on-shell scheme in terms of physical parameters. We present the Hartree-resummed renormalized effective potential at finite temperature and critically discuss the role of the effective potential in a non-equilibrium system. We follow the decay and thermalization of a scalar field from an initial cold state with all energy stored in the potential, into a fully thermalized system with a finite temperature. We identify the non-perturbative processes of parametric resonance and spinodal instability taking place during the reheating stage. In particular we study the unstable modes in the region where the vacuum 1PI effective action becomes complex and show that such spinodal modes can have a dramatic effect on the evolution of the one-point function. Our methods can be easily adapted to simulate reheating at the end of inflation. ...
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Related funder(s)Academy of Finland
Funding program(s)Academy Project, AoF
Additional information about fundingThis work was supported by the Academy of Finland grant 318319. OK was in addition supported by a grant from the Magnus Ehrnrooth Foundation.
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