Two-Loop $\phi^4$-Diagrams from String Theory

TL;DR

This paper demonstrates how to derive two-loop Feynman diagrams for $\

Contribution

It introduces a method to obtain $\

Findings

Successfully reproduces two-loop $\

Connects string theory amplitudes with field theory diagrams

Clarifies the field theory limit of string amplitudes

Abstract

Using the {\em cutting and sewing} procedure we show how to get Feynman diagrams, up to two-loop order, of $\Phi^{4}$-theory with an internal SU(N) symmetry group, starting from tachyon amplitudes of the open bosonic string theory. In a properly defined field theory limit, we easily identify the corners of the string moduli space reproducing the correctly normalized field theory amplitudes expressed in the Schwinger parametrization.