The size of the Proton: Recent Results from the PRad Experiment

Conference · Sat May 01 00:00:00 EDT 2021

OSTI ID:1973250

Gasparian, Ashot ^[1]

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1. North Carolina Ag. and Tech. St. Univ. Greensboro, NC

Two new extremely high precision measurements of the proton rms charge radius performed in 2010-2013 with muonic hydrogen atom demonstrated up to six standard deviations smaller values than the accepted average from all previous experiments performed with different methods (scattering and atomic spectroscopy) on ordinary hydrogen. This discrepancy triggered the well-known ?proton radius puzzle? in hadronic physics. To address this puzzle, the PRad collaboration in spring of 2016 performed a novel magnetic-spectrometer-free ep-scattering experiment in Hall B at Jefferson Lab accumulating high statistics and a rich experimental data set. The specifics of the PRad experiment and the final physics results, including the extracted proton radius, as well as, the current status of the puzzle will be presented and discussed in this talk.

• Research Organization: Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Nuclear Physics (NP)
• DOE Contract Number: AC05-06OR23177
• OSTI ID: 1973250
• Report Number(s): JLAB-PHY-21-3616; DOE/OR/23177-6180
• Resource Relation: Conference: MESON 2021 (16th International Workshop on Meson Physics), May 17, 2021, virtual
• Country of Publication: United States
• Language: English