Cosmological perturbations in SFT inspired non-local scalar field models

TL;DR

This paper investigates cosmological perturbations in non-local scalar field models inspired by string field theory, demonstrating equivalence to local models with multiple scalar fields for free fields.

Contribution

It introduces a method to analyze perturbations in non-local scalar field models and proves their equivalence to local multi-field models in the free field case.

Findings

Energy density perturbation equations match local models for free fields

Establishes a link between non-local and local scalar field perturbations

Provides a framework for analyzing non-local cosmological models

Abstract

We study cosmological perturbations in models with a single non-local scalar field originating from the string field theory description of the rolling tachyon dynamics. We construct the equation for the energy density perturbations of the non-local scalar field and explicitly prove that for the free field it is identical to a system of local cosmological perturbation equations in a particular model with multiple (maybe infinitely many) local free scalar fields.