# Non-Gaussian and loop effects of inflationary correlation functions in BRST formalism

## TL;DR

This paper explores non-Gaussianities and loop effects in inflationary correlation functions using a BRST formalism that maintains covariance, revealing IR logarithmic corrections to slow-roll parameters and implications for inflation models.

## Contribution

It introduces a BRST formalism for inflationary correlation functions that preserves covariance and analyzes IR logarithmic effects on slow-roll parameters at one-loop level.

## Key findings

- IR logarithmic corrections affect the slow-roll parameter epsilon
- No IR logarithmic corrections are found for eta
- The effects suggest a shift symmetry breaking mechanism

## Abstract

We investigate inflationary correlation functions in single field inflation models. We adopt a BRST formalism where locality and covariance at the sub-horizon scale are manifest. The scalar and tensor perturbations are identified with those in the comoving gauge which become constant outside the cosmological horizon. Our construction reproduces the identical non-Gaussianity with the standard comoving gauge. The accumulation of almost scale invariant fluctuations could give rise to IR logarithmic corrections at the loop level. We investigate the influence of this effect on the sub-horizon dynamics. Since such an effect must respect covariance, our BRST gauge has an advantage over the standard comoving gauge. We estimate IR logarithmic effects to the slow-roll parameters at the one-loop level. We show that $\epsilon$ receives IR logarithmic corrections, while this is not the case for $\eta$. We point out that IR logarithmic effects provide the shift symmetry breaking mechanism. This scenario may lead to an inflation model with a linear potential.