Eur. Phys. J. C (2018) 78: 371
https://doi.org/10.1140/epjc/s10052-018-5862-5

Regular Article - Theoretical Physics

Stochastic dark energy from inflationary quantum fluctuations

¹ Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093, Warsaw, Poland
² Institute for Theoretical Physics, Spinoza Institute and EMME𝛷, Faculty of Science, Utrecht University, Postbus 80.195, 3508 TD, Utrecht, The Netherlands
³ L. D. Landau Institute for Theoretical Physics RAS, Moscow, 119334, Russian Federation
⁴ Kazan Federal University, Kazan, 420008, Republic of Tatarstan, Russian Federation

^* e-mail: drazen.glavan@fuw.edu.pl

Received: 23 October 2017
Accepted: 2 May 2018
Published online: 10 May 2018

Abstract

We study the quantum backreaction from inflationary fluctuations of a very light, non-minimally coupled spectator scalar and show that it is a viable candidate for dark energy. The problem is solved by suitably adapting the formalism of stochastic inflation. This allows us to self-consistently account for the backreaction on the background expansion rate of the Universe where its effects are large. This framework is equivalent to that of semiclassical gravity in which matter vacuum fluctuations are included at the one loop level, but purely quantum gravitational fluctuations are neglected. Our results show that dark energy in our model can be characterized by a distinct effective equation of state parameter (as a function of redshift) which allows for testing of the model at the level of the background.