The Proton Radius Puzzle

TL;DR

The paper discusses the proton radius puzzle, a discrepancy between measurements from muonic and regular hydrogen, exploring new theoretical tools to understand proton structure and potential new physics.

Contribution

It introduces novel effective field theoretical methods to connect muonic hydrogen measurements with muon-proton scattering data.

Findings

Development of new effective field theories

Potential insights into proton structure

Implications for new physics involving muons

Abstract

In 2010 the proton charge radius was extracted for the first time from muonic hydrogen, a bound state of a muon and a proton. The value obtained was five standard deviations away from the regular hydrogen extraction. Taken at face value, this might be an indication of a new force in nature coupling to muons, but not to electrons. It also forces us to reexamine our understanding of the structure of the proton. Here I describe an ongoing theoretical research effort that seeks to address this "proton radius puzzle". In particular, I will present the development of new effective field theoretical tools that seek to directly connect muonic hydrogen and muon-proton scattering.