Brane - Anti-Brane Forces

TL;DR

The paper analyzes forces between BPS branes, focusing on brane-antibrane pairs. It employs open-string one-loop annulus amplitudes to compare like-sign and opposite-sign BPS interactions, showing vanishing forces for like-sign but nonzero, complex, brane-antibrane forces at short distances. When the lightest open-string mode becomes tachyonic for $Z<0$, the effective potential $V=Z T^2 + C g^2 T^4$ drives condensation to $T \sim 1/g$, indicating brane-antibrane annihilation into closed strings. The work suggests a qualitative link between this condensate dynamics and black hole formation and entropy, though nonlinear gravitational effects are not included in the calculation.

Abstract

The force between like sign BPS saturated objects generally vanishes. This is a reflection of the fact that BPS states are really massless uncharged particles with nonvanishing momenta in compactified directions. Two like sign BPS objects with zero relative velocity can be viewed as a boosted state of two neutral massless particles in a state of vanishing relative motion. By contrast two unlike sign BPS particles may be thought of as colliding objects moving in opposite directions in compact space. This leads to complicated interactions which are totally intractable at present. We illustrate this by considering the potential between opposite sign zero-D- branes .