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Duke Physics Colloquium: The Proton Remains Puzzling

Feb 19

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Wednesday, February 19, 2020 - 3:30pm to 4:30pm



Haiyan Gao (Duke University Physics Department)

"The Proton Remains Puzzling" Nucleons (protons and neutrons) are the building blocks of atomic nuclei, and are responsible for more than 99% of the visible matter in the universe. Despite decades of efforts in studying its internal structure, there are still a number of puzzles surrounding the proton such as its spin, mass, and charge radius. The proton charge radius puzzle developed about ten years ago refers to a 5-7 sigma discrepancy between the ultrahigh precise values of the proton charge radius determined from muonic hydrogen Lamb shift measurements and the CODATA values compiled from electron-proton scattering experiments and hydrogen spectroscopy measurements. In this talk I will briefly introduce the proton spin and mass puzzles first. I will then focus on the proton charge radius puzzle, the latest experimental results, and especially the PRad experiment at Jefferson Lab and its result. Faculty host: Joshua Socolar Refreshments will be available before the event in room 130. Image credit: Joanna Griffin, Jefferson Lab