15th Conference on the Intersections of Particle and Nuclear Physics (CIPANP 2025) Madison Wisconsin June 9-13

PRad-II and the Proton Radius Puzzle

Jun 10, 2025, 8:30 AM

30m

Plenary presentation Plenary

Speaker

Tyler Hague (Thomas Jefferson National Accelerator Facility)

Description

A greater than 5σ discrepancy in the measurement of the proton charge radius from the accepted value (0.88 fm) due to muonic hydrogen spectroscopy measurements (in 2010 and 2013) sparked the proton radius puzzle. Since then, many experiments have set out to measure the proton radius in an effort to elucidate the reason for this new disagreement. One such experiment was PRad (Proton Radius) which used a novel magnet-free spectrometer to record the proton electric form factor low as 2x10${}^{-4}$ GeV${}^2$ in four-momentum transfer squared (Q${}^2$). The results were the first electron scattering measurements to agree with the muonic hydrogen results of a small (0.84 fm) radius. In this talk, I will discuss the upcoming follow-up experiment, PRad-II, that will record data as low as Q2=10${}^{-5}$ GeV${}^2$ in order to further understand this puzzle and the differences between data sets.

Presentation materials

Hague-PRad-II-CIPANP2025_final.pdf