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arXiv · hep-th/9506022

Feynman rules for string field theories with discrete target space

Saburo Higuchi·Ivan K. Kostov
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Abstract

We derive a minimal set of Feynman rules for the loop amplitudes in unitary models of closed strings, whose target space is a simply laced (extended) Dynkin diagram. The string field Feynman graphs are composed of propagators, vertices (including tadpoles) of all topologies, and leg factors for the macroscopic loops. A vertex of given topology factorizes into a fusion coefficient for the matter fields and an intersection number associated with the corresponding punctured surface. As illustration we obtain explicit expressions for the genus-one tadpole and the genus-zero four-loop amplitude.

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Saburo Higuchi, Ivan K. Kostov. 1995-06-14. Feynman rules for string field theories with discrete target space. https://doi.org/10.1016/0370-2693(95)00878-o

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