D-branes in a Big Bang/Big Crunch Universe: Misner Space

TL;DR

This paper investigates the behavior of D-branes in a time-dependent Misner space, revealing phenomena like string pair creation and emission linked to the universe's big bang/big crunch singularity.

Contribution

It provides a detailed analysis of D-branes in Misner space, including their dynamics, string emission processes, and scattering amplitudes, highlighting novel time-dependent effects.

Findings

Imaginary parts of partition functions indicate string pair creation and emission.

D0-branes follow spiral orbits in Misner space.

Open string scattering is less singular than closed string scattering.

Abstract

We study D-branes in a two-dimensional Lorentzian orbifold R^{1,1}/\Gamma with a discrete boost \Gamma. This space is known as Misner or Milne space, and includes big crunch/big bang singularity. In this space, there are D0-branes in spiral orbits and D1-branes with or without flux on them. In particular, we observe imaginary parts of partition functions, and interpret them as the rates of open string pair creation for D0-branes and emission of winding closed strings for D1-branes. These phenomena occur due to the time-dependence of the background. Open string 2 -> 2 scattering amplitude on a D1-brane is also computed and found to be less singular than closed string case.