Physics Colloquium Series (10.24) | Haiyan Gao

Thursday, October 24, 2019 at 4:00pm to 5:00pm

Huntington Hall (10-250), 10-250

The David and Edith Harris Physics Colloquium Series

Speaker: Haiyan Gao | Duke University

"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. While major progress has been made in the last three decades in understanding the proton spin "crisis'', which originated in the late 1980s by the European Muon Collaboration experiment, the nature of proton spin remains puzzling. Another proton puzzle developed in recent years concerns the proton charge radius. The ultrahigh precise value of the proton charge radius determined from muonic hydrogen Lamb shift measurements is significantly smaller than the values determined from electron-proton scattering experiments and the CODATA value of the hydrogen spectroscopy measurements. In this talk I will introduce the proton spin, mass puzzle first, and then focus on the proton charge radius, the PRad experiment at Jefferson Lab and its result on the proton charge radius.


The lecture will take place in 10-250, starting at 4pm.
Pre-Colloquium Social in room 4-349 will begin at 3:30pm, refreshments will be served.

For questions, contact Ryan Higgins at

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