Cosmological Coleman-Weinberg Potentials and Inflation

TL;DR

This paper investigates the impact of quantum matter fluctuations on inflationary models, revealing that Coleman-Weinberg potentials can significantly alter inflation dynamics and reheating, with effects depending on matter coupling types.

Contribution

It introduces the problem of nonlocal Coleman-Weinberg potentials in inflation and analyzes their effects through a simple subtraction scheme, highlighting their influence on inflationary evolution.

Findings

Fermionic corrections reduce the Hubble parameter during inflation.

Gauge boson corrections can prematurely end inflation unless gauge charges are very small.

Quantum fluctuations induce nonlocal potentials that cannot be fully subtracted locally.

Abstract

We consider an additional fine-tuning problem which afflicts scalar-driven models of inflation. The problem is that successful reheating requires the inflaton be coupled to ordinary matter, and quantum fluctuations of this matter induces Coleman-Weinberg potentials which are not Planck-suppressed. Unlike the flat space case, these potentials depend upon a still-unknown, nonlocal functional of the metric which reduces to the Hubble parameter for de Sitter. Such a potential cannot be completely subtracted off by any local action. In a simple model we numerically consider one possible subtraction scheme in which the correction is locally subtracted at the beginning of inflation. For fermions the effect is to make the universe approach de Sitter with a smaller Hubble parameter. For gauge bosons the effect is to make inflation end almost instantly unless the gauge charge is unacceptably small.