Phase transitions during Cyclic-Inflation and Non-gaussianity

TL;DR

This paper explores phase transitions in cyclic inflation models, highlighting how thermal effects and critical phenomena can produce significant non-Gaussianities observable in the cosmic microwave background.

Contribution

It introduces the impact of phase transitions on non-Gaussianity signatures within cyclic inflation, a novel aspect not present in standard cold inflation models.

Findings

Phase transitions can lead to large non-Gaussianities near critical temperature.

Higher order correlations diverge as the critical temperature is approached.

Thermal effects imprint observable signatures in the CMBR.

Abstract

Typically cold inflation with positive vacuum energy density dilutes all matter except the quan- tum fluctuations which are stretched outside the Hubble patch during inflation. However the cyclic- inflation scenario, where the universe undergoes many many asymmetric cycles leading to an overall exponential growth, operates in the presence of thermal matter. Thus, while some of the nice prop- erties of cold inflation is preserved, in cyclic inflationary models thermal excitations are continually produced and there exists a unique opportunity of imprinting interesting thermal history in CMBR. In particular, we will see that a phase transition can lead to observably large higher order nongaus- sianities as the critical temperature is approached, and that these are increasingly divergent with the order of the correlations.