Proton radius puzzle and large extra dimensions

TL;DR

This paper proposes a theoretical model involving large extra dimensions and modified gravity to explain the proton radius puzzle by accounting for energy shifts in muonic hydrogen experiments.

Contribution

It introduces a novel framework combining extra dimensions and modified gravity to resolve discrepancies in proton radius measurements.

Findings

Energy shift explains the proton radius discrepancy

Constraints on the range of the new gravitational force

Potential for testing new physics at small scales

Abstract

We propose a theoretical scenario to solve the proton radius puzzle which recently arises from the muonic hydrogen experiment. In this framework, 4 + n dimensional theory is incorporated with modified gravity. The extra gravitational interaction between the proton and muon at very short range provides an energy shift which accounts for the discrepancy between spectroscopic results from muonic and electronic hydrogen experiments. Assuming the modified gravity is a small perturbation to the existing electromagnetic interaction, we find the puzzle can be solved with stringent constraint on the range of the new force. Our result not only provides a possible solution to the proton radius puzzle but also suggest a direction to test new physics at very small length scale.