Model Independent Signatures of New Physics in the Inflationary Power Spectrum

TL;DR

This work derives universal, model-independent corrections to the inflationary power spectrum from unknown high-energy physics by integrating out a massive field in a time-dependent background using the in-in formalism. The leading corrections are linear in $H/M$, yielding a scale-invariant enhancement of the spectrum and can be encapsulated in a generalized boundary effective field theory localized on the New Physics Hypersurface. The analysis connects microscopic high-energy scenarios (NPH/BEFT) to observable cosmological signatures, offering a robust framework for potential Planck-scale imprints while clarifying when oscillatory features are not generic after renormalization. Overall, the paper provides a concrete method to map high-energy physics onto the inflationary power spectrum with potential observational relevance.

Abstract

We compute the universal generic corrections to the inflationary power spectrum due to unknown high-energy physics. We arrive at this result via a careful integrating out of massive fields in the "in-in" formalism yielding a consistent and predictive low-energy effective description in time-dependent backgrounds. We find that the power spectrum is universally modified at order H/M, where H is the scale of inflation. This is qualitatively different from the universal corrections in time-independent backgrounds, and it suggests that such effects may be present in upcoming cosmological observations.

Figures (1)

• Figure 1: Power spectrum corrections mediated by the heavy field. Single solid lines indicate contractions of ${\bar{\varphi}}$, dashed single lines indicate those of $\Phi$, with analogous notation for double lines indicating the heavy field components $\{ {\bar{\chi}},{\rm X} \}$.