The Physics & Astronomy Colloquium Series presents Paul King of Ohio University, discussing "Through a Glass Weakly: Studies in Parity Violation at Jefferson Lab" on September 13.

Abstract: In this talk, I will describe how Ohio University students and I have used and will use parity violating electron scattering at Jefferson Lab to probe both the physics of nuclei and the existence of new particles at energies comparable to those achievable at the Large Hadron Collider. 

I will explain how the parts-per-billion asymmetries we measure can reveal the distribution of neutrons inside the nucleus and could indicate the presence of new forces between quarks.  I will discuss three completed PV experiments, Qweak, PREX-II, CREX, and one upcoming experiment, MOLLER.  The PREX-II and CREX asymmetries are used to extract the difference in the radial distribution of the protons and neutrons in Pb-208 and Ca-48 nuclei respectively, which is related to the “stiffness” of nuclear matter.  This measurement of the equation of state of nuclear matter is not just important to understand nuclei, but can be applied to the properties of neutron stars.  Qweak and MOLLER are tests of the Standard Model of particle physics, using the nearly zero weak charge of the proton and electron to search for evidence of new physics.  Qweak measured an asymmetry consistent with the Standard Model prediction, pushing the lower mass limit on new semi-leptonic parity-violation physics to above 3.5 TeV.  MOLLER’s measurement is expected to be sensitive to particles contributing to the electron-electron scattering of masses around 7.5 TeV.