Time Lumps in Nonlocal Stringy Models and Cosmological Applications

TL;DR

This paper investigates lump solutions in nonlocal string-inspired models and explores their potential cosmological applications, focusing on local approximations and phantom behavior at large times.

Contribution

It introduces a local approximation method for nonlocal models and analyzes the validity of this approximation in cosmological contexts.

Findings

Large-time solutions exhibit phantom behavior.

The local approximation is valid under certain conditions.

Explicit time lump solutions are constructed in flat backgrounds.

Abstract

We study lump solutions in nonlocal toy models and their cosmological applications. These models are motivated by a description of D-brane decay within string field theory framework. In order to find cosmological solutions we use the simplest local approximation keeping only second derivative terms in nonlocal dynamics. We study a validity of this approximation in flat background where time lump solutions can be written explicitly. We work out the validity of this approximation. We show that our models at large time exhibit the phantom behaviour similar to the case of the string kink.