Ultraviolet and Infrared freedom from string amplitudes

TL;DR

This paper investigates the infinite tension limit of string amplitudes, revealing mechanisms behind diamagnetic and asymptotic freedom behaviors, and connects string theory representations of abelian gauge theories with non-planar amplitudes and beta functions.

Contribution

It identifies the specific parts of string amplitudes responsible for diamagnetic and paramagnetic behaviors and links string theory to gauge theory beta functions through non-planar amplitudes.

Findings

Identification of diamagnetic and paramagnetic contributions in string amplitudes

Connection between string theory and abelian gauge theories via non-planar amplitudes

Discovery of a nontrivial beta function in the low energy limit of a D-brane

Abstract

The infinite tension limit of string amplitudes is examined with some care, identifying the part responsible of diamagnetic behaviour as well as a peculiar paramagnetic {\em tachyon magnifying} responsible of asymptotic freedom. The way string theory represents abelian gauge theories is connected with the non-planar reggeon/pomeron amplitude and a nontrivial beta function is found in the low energy limit of a single D-brane.