Vacuum arbitrariness and the Hubble tension

Abstract

We show that the energy density of the superhorizon modes released in a non-Bunch-Davies vacuum can be arbitrarily large during inflation and it decreases like ln(a)/a^4 in the subsequent radiation dominated era. This may constitute a dark radiation component which can sufficiently alter the early cosmological evolution to alleviate the Hubble tension.

18 pages, 2 figures, v2: references added

References in corpus (2)

• The trouble with $H_0$
• Early dark energy, the Hubble-parameter tension, and the string axiverse