Alpha-states in de Sitter space

TL;DR

This paper explores alpha-states in de Sitter space, their unique properties, potential observational signatures in inflation, and implications for gravitational interactions and string theory vacua.

Contribution

It introduces a formalism for alpha-states in de Sitter space, analyzes their properties, and discusses their potential observational and theoretical implications.

Findings

Alpha-states exhibit non-local correlations.

Alpha-states can produce momentum-dependent corrections to inflationary spectra.

Extension to spin-2 fields suggests new infrared gravitational effects.

Abstract

Field theory in de Sitter space admits a one-parameter family of vacua determined by a superselection parameter alpha. Of these vacua, the Euclidean vacuum uniquely extrapolates to the vacuum of flat Minkowski space. States which resemble the alpha-vacua can be constructed as excitations above the Euclidean vacuum. Such states have modes alpha(k) which decay faster that k^{(1-d)/2}. Fields in such states exhibit non-local correlations when examined from the perspective of fields in the Euclidean vacuum. The dynamics of such entangled states are fully consistent. If an alpha-state with properties that interpolate between an alpha-vacuum and the Euclidean vacuum were the initial condition for inflation, a signature for this may be found in a momentum dependent correction to the inflationary power spectrum. The functional formalism, which provides the tool for examining physics in an alpha-state, extends to fields of other spin. In particular, the extension to spin-2 may proffer a new class of infrared modifications to gravitational interactions. The implications of superselection sectors for the landscape of string vacua are briefly discussed.