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arXiv · 2005.05877

Double-soft behavior of massless closed strings interacting with any number of closed string tachyons

Raffaele Marotta·Matin Mojaza
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Abstract

We calculate the simultaneous double-soft limit of two massless closed strings scattering with any number of closed string tachyons to the subleading order at the tree level. The limit factorizes the scattering amplitude into a double-soft factor multiplying the pure tachyon subamplitude, suggesting a universal double-soft theorem for the massless closed string. We confirm an existing result for the double-soft graviton in an on-shell equivalent, but different form, while also establishing the double-soft factorization behavior of the string dilaton and of the Kalb-Ramond state, as well as the mixed graviton-dilaton case. We also show that the simultaneous and consecutive double-soft theorems are consistent with each other. We furthermore provide a complete field theory diagrammatic view on our result, which enables us in particular to establish a four-point interaction vertex for two tachyons and two massless closed string states, as well as the missing in field theory of three-point interaction of two massless closed string state and one tachyon.

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Raffaele Marotta, Matin Mojaza. 2020-05-12. Double-soft behavior of massless closed strings interacting with any number of closed string tachyons. https://arxiv.org/abs/2005.05877

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