Constraining first-order phase transitions with curvature perturbations

TL;DR

This paper explores how quantum tunneling during early universe phase transitions affects curvature perturbations and uses cosmic microwave background data and minihalo observations to constrain the properties of these phase transitions, especially at low energies.

Contribution

It introduces a novel method of constraining first-order phase transition parameters using curvature perturbations and observational data.

Findings

Constraints on phase transition parameters below 100 GeV.

Stronger limits on low-scale and weak phase transitions.

Current bounds on phase transitions are significantly improved.

Abstract

We investigate the curvature perturbations induced by the randomness of the quantum tunneling process during cosmological first-order phase transitions (PTs) and for the first time ultilize curvature perturbations to constrain the PT parameters. We find that the observations of the cosmic microwave background spectrum distortion and the ultracompact minihalo abundance can give strict constraints on the PTs below 100GeV, especially for the low-scale PTs and the weak PTs. The current constraint on the PT parameters is largely extended by the results in this work.