Abstract
We compute one-loop threshold corrections toℛ4terms inN=5,6supergravity vacua of Type II superstrings. We then discuss nonperturbative corrections generated by asymmetric D-brane instantons. Finally we derive generating functions for MHV amplitudes at tree level inN=5,6supergravities.
Highlights
N 5, 6 supergravities in D 4 enjoy many of the remarkable properties of N 8 supergravity
The threshold corrections that we find may be taken as evidence that, as in the N 8 case, superstring calculations do not reproduce field theory results, where such R4 corrections are absent as a result of the unbroken anomaly free continuous U-duality symmetry as in the N 8 case 1
Since N 5, 6 supergravities can be obtained as asymmetric orbifolds of tori, tree-level scattering amplitudes of untwisted states such as gravitons are identical to the corresponding amplitudes in the parent N 8 theory
Summary
N 5, 6 supergravities in D 4 enjoy many of the remarkable properties of N 8 supergravity. The threshold corrections that we find may be taken as evidence that, as in the N 8 case, superstring calculations do not reproduce field theory results, where such R4 corrections are absent as a result of the unbroken anomaly free continuous U-duality symmetry as in the N 8 case 1. This is in line with the nondecoupling in Type II superstrings of BPS states that are singular from the strict 4-dimensional supergravity perspective 8–10. We will only focus on R4 terms in D 4 the parent D 5 theory is instrumental to the identification of the relevant BPS instantons
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