Axion production from gravitons off interacting 0-branes

TL;DR

This paper investigates axion production via graviton interactions in a two D0-brane system within superstring theory, revealing a non-zero amplitude mediated by RR states, which is absent in single-brane scenarios.

Contribution

It demonstrates axion production from graviton interactions in a two-brane system, highlighting the role of RR state exchange and compactification effects.

Findings

Non-zero axion production amplitude in two-brane system

Amplitude arises from RR state exchange in odd spin sector

Leading order amplitude matches field theory expectations

Abstract

We study axion-graviton scattering from a system of two D$0$-branes in a Type II superstring theory, a process which does not occur on a single brane. The two D$0$-branes interact via the exchange of closed string states which form a cylinder joining them. By compactifying on the $Z_3$ orbifold we find a non vanishing amplitude coming from the odd spin structure sector, thus from the exchanged RR states. We compute, in particular, the leading term of the amplitude at large distance from the branes, which corresponds to taking a field theory limit. This seems to suggest that the process takes place through the coupling of an axion to the RR states exchanged between the 0-branes.