Quantum corrections to the primordial tensor spectrum: Open EFTs & Markovian decoupling of UV modes

TL;DR

This paper develops an open quantum system approach to compute first-order quantum corrections to the primordial tensor spectrum, highlighting the importance of Markovian assumptions and providing a systematic framework for future relaxations.

Contribution

It introduces a novel open EFT framework for tensor spectrum corrections, extending beyond standard loop calculations and addressing non-Markovian effects.

Findings

Results match standard loop corrections in the Markovian limit

Establishes a systematic method to relax Markovian approximation

Highlights the importance of non-Markovian effects in gravitational systems

Abstract

Perturbative quantum corrections to primordial power spectra are important for testing the robustness and the regime of validity of inflation as an effective field theory. Although this has been done extensively for the density power spectrum (and, to some extent, for the tensor spectrum) using loop corrections, we do so in an open quantum system approach to the problem. Specifically, we calculate the first order corrections to the primordial gravitational wave spectrum due to (cubic) tensor interactions alone. We show that our results match expectations from standard loop corrections only in the strict Markovian limit, and therefore, establish a systematic way to relax this approximation in the future, as is generally necessary for gravitational systems.