Route to nonlocal cosmology

TL;DR

This paper introduces an analytic method for solving nonlocal cosmological models inspired by string theory, enabling the study of complex scalar field dynamics with infinite derivatives in various cosmological settings.

Contribution

It develops a systematic localization algorithm for nonlocal actions and explores solutions in cosmological models, expanding the understanding of nonlocal dynamics in early universe scenarios.

Findings

Successfully localized nonlocal models for cosmology

Identified general features of nonlocal scalar field dynamics

Provided solutions in braneworld and standard cosmological backgrounds

Abstract

An analytic approach to phenomenological models inspired by cubic string field theory is introduced and applied to some examples. We study a class of actions for a minimally coupled, homogeneous scalar field whose energy density contains infinitely many time derivatives. These nonlocal systems are systematically localized and an algorithm to find cosmological solutions of the dynamical equations is provided. Our formalism is able to define the nonlocal field in regions of the parameter space which are inaccessible by standard methods. Also, problems related to nonlocality are reinterpreted under a novel perspective and naturally overcome. We consider phenomenological models living on a Friedmann-Robertson-Walker background with power-law scale factor, both in four dimensions and on a high-energy braneworld. The quest for solutions unravels general features of nonlocal dynamics indicating several future directions of investigation.