Regge Closed String Scattering and its Implication on Fixed angle Closed String Scattering

TL;DR

This paper computes complete high energy scattering amplitudes for closed strings in the Regge regime and derives fixed angle ratios, revealing new insights into string scattering behavior at high energies.

Contribution

It provides the first complete calculation of fixed angle closed string scattering amplitudes using Stirling number identities, overcoming previous computational limitations.

Findings

Derived complete ratios among closed string high energy amplitudes in the fixed angle regime.

Contrasts with previous incomplete calculations lacking zero-norm state input.

Highlights the role of Stirling numbers in string amplitude calculations.

Abstract

We calculate the complete closed string high energy scattering amplitudes (HSA) in the Regge regime for arbitrary mass levels. As an application, we deduce the complete ratios among closed string HSA in the fixed angle regime by using Stirling number identities. These results are in contrast with the incomplete set of closed string HSA in the fixed angle regime calculated previously. The complete forms of the fixed angle amplitudes, and hence the ratios, were not calculable previously without the input of zero-norm state calculation. This is mainly due to the lack of saddle point in the fixed angle closed string calculation.