Gravitational couplings of orientifold planes

TL;DR

This paper reexamines the gravitational couplings of orientifold planes and D-branes, computing instantonic corrections and deriving Wess-Zumino terms using dualities, with partial validation from M-theory.

Contribution

It provides new calculations of instanton corrections and Wess-Zumino terms for orientifold planes, clarifying previous oversimplifications and highlighting ongoing challenges.

Findings

Computed D_{-1} instantonic corrections for p=3

Derived Wess-Zumino terms for orientifolds with RR flux for p ≤ 5

Identified difficulties in computing 7 Brane instanton corrections

Abstract

We reanalyse the gravitational couplings of the perturbative orientifold planes $Op^-$, $Op^+$ (and D-branes). We first compute their $D_{-1}$ instantonic corrections for $p=3$. Then, by using U-dualities, we obtain the Wess-Zumino terms of orientifolds with RR flux for $p \leq 5$. The expressions for the effective actions can be partially checked via M-theory. We point out a previous oversimplification and we show in fact that the difficulty still stands in the way of the full computation of 7 Brane instanton corrections.