String theory predictions for future accelerators

TL;DR

This paper explores string theory predictions for collider signatures involving low string scale models, focusing on virtual gravitational exchanges and graviton emissions, and provides calculations of string corrections to field theory results.

Contribution

It introduces a regularization scheme for virtual graviton exchanges and computes exact string amplitudes, highlighting deviations from field theory in low string scale scenarios.

Findings

Regularization of Kaluza-Klein sums in string theory.

Leading string corrections to gravitational amplitudes.

Exact string amplitude calculations showing deviations from field theory.

Abstract

We consider, in a string theory framework, physical processes of phenomenological interest in models with a low string scale. The amplitudes we study involve tree-level virtual gravitational exchange, divergent in a field-theoretical treatment, and massive gravitons emission, which are the main signatures of this class of models. First, we discuss the regularization of summations appearing in virtual gravitational (closed string) Kaluza-Klein exchanges in Type I strings. We argue that a convenient manifestly ultraviolet convergent low energy limit of type I string theory is given by an effective field theory with an arbitrary cutoff $\Lambda$ in the closed (gravitational) channel and a related cutoff $M_s^2/\Lambda$ in the open (Yang-Mills) channel. We find the leading string corrections to the field theory results. Second, we calculate exactly string tree-level three and four-point amplitudes with gauge bosons and one massive graviton and examine string deviations from the field-theory result.