Title： The Puzzles Surrounding Proton Still
Speaker: Haiyan Gao (Vice Chancellor for Academic Affairs, Duke Kunshan University, Henry Newson Professor of Physics at Duke University)
Institute: Duke Kunshan University
Time：15:00-16:00, 19.12.2018 (Wednesday)
Place： Physics Building 307, Haiyun Campus, Xiamen University
Nucleons (protons and neutrons) are building blocks of visible matter, and are responsible for more than 99% of the visible mass in the universe. However, not only we know little about its internal structure, there are also a number of puzzles surrounding the properties of proton such as its spin, mass and charge radius. Despite major progresses made in the last two decades in understanding the proton spin ``crisis'' discovered in the late 1980s by the European Muon Collaboration, the proton spin remains puzzling. Another proton puzzle developed in the last several years concerning the proton charge radius, which is the charge distribution weighted size of the proton. 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 Lamb shift measurements. In this talk I will introduce the proton spin, mass puzzles first briefly and then focus on the latest concerning the proton charge radius puzzle and the PRad experiment at Jefferson Lab in the United States.
Haiyan Gao was born in Shanghai, China. She received her B.S. degree from Tsinghua University in 1988 and Ph.D. in Physics from Caltech in 1994. She was a Postdoctoral Research Associate at the University of Illinois, Urbana-Champaign from 1994-1996 and then joined the scientific staff at the Argonne National Laboratory in 1996. She became an Assistant Professor of Physics at MIT in 1997 and was promoted to Associate Professor in 2002. She joined the Physics faculty of Duke in 2002 and became a full Professor in 2008. She was named Henry Newson Professor of Physics in 2012 at Duke. From 2006-2009, she was the Associate Chair for Teaching in Physics at Duke, and was the Chair of the department from 2011 to 2014. In January 2015, she became the Vice Chancellor for Academic Affairs at the Duke Kunshan University.
Her research interests cover the structure of the nucleon, search for Quantum Chromodynamics (QCD) exotic states, fundamental symmetry studies at low energy to search for new physics beyond the Standard Model of electroweak interactions, and the developments of polarized targets. She received a number of awards including being elected as a Fellow of the American Physical Society in 2007 and winning the Outstanding Junior Investigator Award by the US Department of Energy in 2000. She has published many papers in peer-reviewed journals, and has given numerous invited conference talks, seminars and colloquia worldwide. She chaired and co-chaired many workshops and conferences, and she has served on many international advisory committees and panels, professional society committees, and editorial boards of journals.