Superhorizon Curvature Perturbations Are Protected against One-Loop Corrections

Area of Science:

• Cosmology
• Theoretical Physics
• Inflationary Cosmology

Background:

• Single-field inflation models are a leading paradigm for the early Universe.
• Small-scale curvature perturbations have been a subject of recent theoretical debate.
• Understanding these perturbations is crucial for refining inflationary models.

Purpose of the Study:

• To investigate one-loop corrections to superhorizon curvature perturbations in single-field inflation.
• To analyze models with transitions between slow-roll (SR) and intermediate periods (ultra-slow-roll or resonant amplification).
• To resolve controversies regarding the behavior of superhorizon perturbations.

Main Methods:

• Examination of one-loop corrections from small-scale to superhorizon curvature perturbations.
• Analysis of inflationary models with SR→intermediate→SR transitions.
• Assumption of superhorizon curvature perturbation conservation during SR periods.

Main Results:

• One-loop corrections from small-scale perturbations to superhorizon ones were analyzed.
• Models with intermediate periods (ultra-slow-roll or resonant amplification) were considered.
• It was shown that superhorizon curvature perturbations coincide at one-loop level in the first and second SR periods.

Conclusions:

• The study demonstrates the consistency of superhorizon curvature perturbations across different slow-roll phases.
• This finding helps resolve recent controversies in single-field inflation models.
• The framework provides a robust understanding of perturbation evolution during complex inflationary histories.