We identify and evaluate a class of physical amplitudes in four-dimensional N = 4 superstring theory, which receive, in the weak coupling limit, contributions of order e−1/λ, where λ is the type II superstring coupling constant. They correspond to four-derivative Ƒ˜1 interaction terms involving the universal type II dilaton supermultiplet. The exact result, obtained by means of a one-loop computation in the dual heterotic theory compactified on T⁶, is compared with the perturbation theory on the type II side, and the e−1/λ contributions are associated to non-perturbative effects of Euclidean solitons (D-branes) wrapped on K3 × T2. The ten-dimensional decompactification limit on the type IIB side validates the recent conjecture for the D-instanton–induced R4 couplings.


Originally posted at http://arxiv.org/abs/hep-th/9707222v2. Preprint of an article published in Nuclear Physics B, v.512, no.1-2, 1998.


four-dimensional superstring theory, high energy physics theory

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Superstring theories, Particles (Nuclear physics)



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