Dr. Daria Sokhan
(Uni. of Glasgow; CEA Saclay)
Monday, August 29, 2022
1 – 2 PM
Venue: GL100A

Abstract: Nucleons -- protons and neutrons, which make up the nuclei of all elements -- provide over 99% of the mass of the visible universe. The study of their structure, which started over 50 years ago with electron scattering from a hydrogen nucleus at the Stanford Linear Accelerator, has shown that they have an extended size and are composed of quarks and gluons, bound by the Strong force. In parallel, the Quark Model seemed to explain the nucleon's properties -- its charge and spin -- by a combination of three constituent quarks. The more the nucleon was studied, however, the more bizarre it appeared: deep inelastic scattering showed that the nucleon could look as if it was made up of three quarks or a sea of gluons and quark-anti-quark pairs, depending on how "deeply" inside it one looked. These studies opened more and more questions. The bare mass of quarks is but a small fraction of the mass of the nucleon, how is its apparent mass generated by the dynamics of quarks and gluons within it? What gives a nucleon its spin, apart from the intrinsic spin of quarks, which contribute only about a third? How are the quarks and gluons distributed inside the nucleon? Fundamental questions such as these about the nature of matter are being addressed at electron scattering facilities around the world. This talk will discuss how experiments at Jefferson Laboratory in Virginia and the Electron-Ion Collider, to be built at Brookhaven Laboratory on Long Island within this decade, help to unravel the mysteries of the nucleon.

Short Bio: Dr. Sokhan graduated from Cambridge University and obtained her PhD in nuclear physics from Edinburgh University. After postdoctoral appointments at Pavia and IPN Orsay, she joined the faculty of Glasgow University in 2013 where she currently is a senior lecturer. After being awarded the 2020 Blaise Pascal Chair of International Excellence from the Île-de-France Region, she is currently spending an extended sabbatical at CEA Saclay. Dr. Sokhan is a member of the Jefferson Lab CLAS12 collaboration and a member of the electron-ion collider user group steering committee. Her research interest focuses on the 3D tomography of the nucleon.