Dynamical F-strings intersecting D2-branes in type IIA supergravity

TL;DR

This paper constructs exact time-dependent solutions describing intersecting F-strings and D2-branes in type IIA supergravity, exploring their dynamics, singularities, and potential applications in cosmological models with power-law expanding universes.

Contribution

It provides new exact solutions for intersecting F-strings and D2-branes with time dependence, and discusses their relevance to cosmology.

Findings

Singularities typically occur before F-string collision.

A special case with equal charges and smeared directions avoids singularities.

Solutions can be compactified to produce power-law expanding FRW universes.

Abstract

We present time-dependent exact solutions composed of F-strings intersecting D2-branes in type IIA supergravity. The F-strings tend to approach each other with time in the six-dimensional space transverse to both F-strings and D2-branes. In general, a singularity appears before collision. An exceptional case is that the charges are the same and five directions in the transverse space are smeared out. Then we argue some applications of the solutions in building cosmological models. The possible models are classified based on compactifications of the internal space. All of them give rise to the Friedmann-Robertson-Walker universe with a power-law expansion.