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arXiv · 1306.2501

The structure of the R^8 term in type IIB string theory

Anirban Basu
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Abstract

Based on the structure of the on-shell linearized superspace of type IIB supergravity, we argue that there is a non--BPS 16 derivative interaction in the effective action of type IIB string theory of the form (t_8 t_8 R^4)^2, which we call the R^8 interaction. It lies in the same supermultiplet as the G^8 R^4 interaction. Using the KLT relation, we analyse the structure of the tree level eight graviton scattering amplitude in the type IIB theory, which leads to the R^8 interaction at the linearized level. This involves an analysis of color ordered multi-gluon disc amplitudes in the type I theory, which shows an intricate pole structure and transcendentality consistent with various other interactions. Considerations of S-duality show that the R^8 interaction receives non-analytic contributions in the string coupling at one and two loops. Apart from receiving perturbative contributions, we show that the R^8 interaction receives a non-vanishing contribution in the one D-instanton-anti-instanton background at leading order in the weak coupling expansion.

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Anirban Basu. 2014-02-02. The structure of the R^8 term in type IIB string theory. https://doi.org/10.1088/0264-9381%2F30%2F23%2F235028

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