Strings from Almost Nothing

TL;DR

This paper demonstrates that string theory amplitudes naturally arise from basic scattering assumptions, establishing their uniqueness through consistency conditions and high-energy behavior analysis.

Contribution

It proves that the Veneziano and Virasoro-Shapiro amplitudes are uniquely determined by minimal consistency and high-energy assumptions, showing string theory's inevitable emergence.

Findings

String amplitudes are uniquely fixed by consistency conditions.

Veneziano and Virasoro-Shapiro amplitudes are the only solutions under these assumptions.

The approach extends to five-point scattering, reinforcing the results.

Abstract

We argue that string theory emerges inevitably from a few simple assumptions about physical scattering. Consistency alone requires that all tree-level four-point scattering amplitudes exhibit vanishing residues at prescribed values of the momentum transfer. Assuming ultrasoft high-energy behavior, we then prove that the space of minimally consistent amplitudes, whose residues exhibit these mandated zeros and nothing more, are precisely the amplitudes of Veneziano and Virasoro-Shapiro, thus establishing the uniqueness of strings. Similar logic also applies to five-point scattering.