Dynamical brane with angles : Collision of the universes

TL;DR

This paper derives time-dependent solutions for dynamical D-branes with angles in supergravity, constructs cosmological models from these solutions, and analyzes brane collision dynamics, including conditions for universe collisions.

Contribution

It introduces new dynamical D-brane solutions with angles that differ from previous intersecting brane solutions, enabling cosmological modeling and collision analysis.

Findings

Power-law FLRW cosmological solutions obtained from brane configurations.

Branes approach each other over time in contracting spacetimes.

Certain smeared or special brane systems can collide without singularities.

Abstract

We present the time-dependent solutions corresponding to the dynamical D-brane with angles in ten-dimensional type II supergravity theories. Our solutions with angles are different from the known dynamical intersecting brane solutions in supergravity theories. Because of our ansatz for fields, all warp factors in the solutions can depend on time. Applying these solutions, we construct cosmological models from those solutions by smearing some dimensions and compactifying the internal space. We find the Friedmann-Lemaitre-Robertson-Walker (FLRW) cosmological solutions with power-law expansion. We also discuss the dynamics of branes based on these solutions. When the spacetime is contracting in ten dimensions, each brane approaches the others as the time evolves. However, for Dp-brane ($p\le 7$) without smearing branes, a singularity appears before branes collide. In contrast, the D6-D8 brane system or the smeared D(p-2)-Dp brane system with one uncompactified extra dimension can provide an example of colliding branes (and collision of the universes), if they have the same charges.