Multifractional spacetimes from the Standard Model to cosmology

TL;DR

This paper reviews recent advances in multifractional spacetimes, exploring their theoretical foundations within the Standard Model and gravity, and discusses observational constraints from particle physics, astrophysics, and cosmology.

Contribution

It provides a comprehensive overview of the theoretical structure and experimental bounds of multifractional spacetimes, highlighting recent progress and constraints.

Findings

Bounds on geometric scales from particle physics

Constraints from cosmic microwave background observations

Implications for gravitational and Standard Model physics

Abstract

We review recent theoretical progress and observational constraints on multifractional spacetimes, geometries that change with the probed scale. On the theoretical side, the basic structure of the Standard Model and of the gravitational action is discussed. On the experimental side, we recall the bounds on the scales of the geometry coming from particle physics, astrophysics, and the cosmic microwave background.