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.
four-dimensional superstring theory, high energy physics theory
Superstring theories, Particles (Nuclear physics)
Antoniadis, I.; Pioline, B.; and Taylor, T. R., "Calculable e−1/λ effects" (1998). Physics Faculty Publications. Paper 48. http://hdl.handle.net/2047/d20000401
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