# Asymptotic safety, string theory and the weak gravity conjecture

## TL;DR

This paper explores a unified framework combining string theory, asymptotic safety, and the Standard Model, proposing a scenario where gravity transitions from a deep ultraviolet string regime to an asymptotically safe intermediate regime, with implications for cosmology and unitarity.

## Contribution

It introduces a novel scenario linking string theory, asymptotic safety, and the Standard Model, and examines the weak gravity conjecture within this framework.

## Key findings

- Potential connection between microscopic and macroscopic cosmological constants.
- Unitarity may be preserved at the asymptotically safe fixed point.
- Conditions on the scales of asymptotic safety and string theory are discussed.

## Abstract

We propose a scenario with string theory in the deep ultraviolet, an intermediate asymptotically safe scaling regime for gravity and matter, and the Standard Model in the infrared. This could provide a new perspective to tackle challenges of the two models: For instance, the gravitational Renormalization Group flow could connect a negative microscopic to a positive macroscopic cosmological constant, potentially rendering string theory on an anti-de Sitter background observationally viable. Further, the unitarity of a string-theoretic ultraviolet completion could be inherited by an asymptotically safe fixed point, despite the presence of higher-order interactions. We discuss necessary conditions on the scale of asymptotic safety and the string scale for our scenario to be viable. As a first test, we explore the weak-gravity conjecture in the context of asymptotically safe gravity.