Unity of cosmological inflation attractors

Area of Science:

• Cosmology and Theoretical Physics
• Inflationary Cosmology
• Quantum Field Theory in Curved Spacetime

Background:

• Recent discoveries reveal broad classes of inflationary models with predictions matching Planck satellite data.
• These models exhibit stability against substantial inflaton potential modifications.
• Some models involve nonminimal coupling to gravity (ξ attractors) or conformal properties (α attractors).

Purpose of the Study:

• To identify the common underlying principle (common denominator) of diverse inflationary attractors.
• To elucidate the origin of robust cosmological predictions across different inflationary models.
• To unify various attractor classes, specifically ξ and α attractors.

Main Methods:

• Analysis of the Einstein frame formulation of inflationary models.
• Investigation of the kinetic term of the inflaton field, particularly a joint pole of order 2.
• Mathematical equivalence established between specific ξ and α attractors.

Main Results:

• The robust predictions of these inflationary models stem from a joint pole of order 2 in the inflaton's kinetic term before canonical transformation.
• Model-dependent variations appear only at subleading orders in the kinetic term.
• A class of ξ attractors is shown to be equivalent to α attractors (α=1+(1/6ξ)).

Conclusions:

• A unified understanding of diverse inflationary attractors is achieved by identifying their shared feature in the kinetic term.
• The study highlights the importance of the inflaton's kinetic term structure for stable cosmological predictions.
• While typically predicting r ~ 1/N², no theoretical lower bound on r exists for the unified class of models.