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Instanton corrections to the effective action of the CHL string and its type I dual

P. Bain
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Abstract

In this letter, we investigate corrections to quartic gauge couplings in compactifications of string theories on a 2-torus without vector structure. First, we calculate the threshold corrections to F^4 terms in the heterotic CHL string. Then, using the CHL string/type I duality dictionary, we map these corrections to perturbative and non-perturbative effects in type I string compactified on 2-torus without vector structure. Comparing the perturbative terms provides a quantitative test of the S-duality conjecture. The non-perturbative contributions are due to D-strings wrapping the torus. A T-duality along one of the compactified directions allows us to compare these instanton corrections to the ones obtained in a standard type I compactifications. The most striking feature is that these non-perturbative couplings turn out to be identical for both models.

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P. Bain. 2002-05-08. Instanton corrections to the effective action of the CHL string and its type I dual. https://arxiv.org/abs/hep-th/0205073

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