Non-Abelian Born–Infeld action and type I–heterotic duality (II): Nonrenormalization theorems Original Research Article

Type I–heterotic duality in D=10 predicts various relations and constraints on higher order Fn couplings at different string loop levels on both sides. We prove the vanishing of two-loop corrections to the heterotic F4 terms, which is one of the basic predictions from this duality. Furthermore, we show that the heterotic F5 and (CP-even) F6 couplings are not renormalized at one loop. These results strengthen the conjecture that in D=10 any TrF2n coupling appears only at the disk tree-level on type I side and at (n−1)-loop level on the heterotic side. Our non-renormalization theorems are valid in any heterotic string vacuum with sixteen supercharges.