Symmetry of String Scattering Amplitudes

Abstract

We explore the hidden symmetry in string theory by studying string scattering amplitudes. We calculate 4-point open string scattering amplitudes with three tachyons and a massive higher spin string state. The result can be expressed as Type D Lauricella functions which are generalization of Gaussian Hypergeometric functions. In various high energy limits, the string amplitudes reduced to the expected results that we obtained previously. We find exact SL (K + 3, C) symmetry for the string amplitudes at general energy.