Dynamical String Tension in String Theory with Spacetime Weyl Invariance

TL;DR

This paper extends the concept of Weyl invariance to string theory, promoting the string tension to a dynamical field, leading to a geodesically complete cosmological model with new early universe implications.

Contribution

It introduces a Weyl-invariant formulation of string theory where the string tension becomes a dynamical field, expanding the theoretical framework and cosmological applications.

Findings

String tension is promoted to a dynamical field.

Weyl invariance is extended to target space background fields.

Proposes a geodesically complete cosmological string background.

Abstract

The fundamental string length, which is an essential part of string theory, explicitly breaks scale invariance. However, in field theory we demonstrated recently that the gravitational constant, which is directly related to the string length, can be promoted to a dynamical field if the standard model coupled to gravity (SM+GR) is lifted to a locally scale (Weyl) invariant theory. The higher gauge symmetry reveals previously unknown field patches whose inclusion turn the classically conformally invariant SM+GR into a geodesically complete theory with new cosmological and possibly further physical consequences. In this paper this concept is extended to string theory by showing how it can be Weyl lifted with a local scale symmetry acting on target space background fields. In this process the string tension (fundamental string length) is promoted to a dynamical field, in agreement with the parallel developments in field theory. We then propose a string theory in a geodesically complete cosmological stringy background which suggests previously unimagined directions in the stringy exploration of the very early universe.