Two Loop Scalar Self-Mass during Inflation

TL;DR

This paper calculates the two-loop quantum corrections to the mass of a scalar field during inflation, revealing a geometry-induced mass growth that impacts the universe's acceleration.

Contribution

It provides the first detailed two-loop calculation of scalar self-mass in an inflating universe, highlighting the effects of de Sitter geometry on mass renormalization.

Findings

Non-zero mass renormalization due to geometry effects.

Growing mass that influences super-acceleration.

Consistent renormalization with flat space results.

Abstract

We work in the locally de Sitter background of an inflating universe and consider a massless, minimally coupled scalar with a quartic self-interaction. We use dimensional regularization to compute the fully renormalized scalar self-mass-squared at one and two loop order for a state which is released in Bunch-Davies vacuum at t=0. Although the field strength and coupling constant renormalizations are identical to those of lfat space, the geometry induces a non-zero mass renormalization. The finite part also shows a sort of growing mass that competes with the classical force in eventually turning off this system's super-acceleration.