Linear relations among 4-point functions in the high energy limit of string theory

TL;DR

This paper extends the linear relations among 4-point functions in high energy string theory from leading order to next-to-leading and higher orders, revealing deeper structural insights.

Contribution

It generalizes the approach of using zero-norm state decoupling to higher orders in the high energy limit of string theory.

Findings

Linear relations hold at next-to-leading order

Ratios among 4-point functions are determined at higher orders

Method confirms the robustness of the linear relation approach

Abstract

The decoupling of zero-norm states leads to linear relations among 4-point functions in the high energy limit of string theory. Recently it was shown that the linear relations uniquely determine ratios among 4-point functions at the leading order. The purpose of this paper is to extend the validity of the same approach to the next-to-leading order and higher orders.