# nLab duality between type I and heterotic string theory

Contents

### Context

#### Duality in string theory

duality in string theory

general mechanisms

string-fivebrane duality

string-string dualities

M-theory

F-theory

string-QFT duality

QFT-QFT duality from wrapped M5-branes:

# Contents

## Idea

one of the dualities in string theory: between type I string theory and heterotic string theory

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## Properties

### Gauge group

For type I string theory on flat target spacetime orientifolds $\mathbb{R}^{9,1}$ RR-field tadpole cancellation requires 32 D-branes to cancel the O-plane charge of -32 (here).

Under the duality between type I and heterotic string theory this translates to the semi-spin gauge group SemiSpin(32) of heterotic string theory.

## References

• Arkady Tseytlin, Heterotic - type I superstring duality and low-energy effective actions, Nucl.Phys.B467:383-398, 1996 (arXiv:hep-th/9512081)

• I. Antoniadis, H. Partouche, T.R. Taylor, Lectures on Heterotic-Type I Duality, Nucl.Phys.Proc.Suppl. 61A (1998) 58-71 (arXiv:hep-th/9706211)