Current Schedule

Speaker = Prof. Caryn Palatchi of Indiana University of Bloomington

Host = Jaideep Taggart Singh singhj@frib.msu.edu

When = 2025-03-12 Wednesday

Where = FRIB 1300

Please feel free to sign up below, but note that some slots may need to be re-assigned to accommodate those with a specific need to meet the speaker. If this happens, the Admin or Speaker Host will reach out to you via email.

Title = Precision Parity Violating Electron Scattering Experiments

Abstract

The RMS radii of the neutron distribution in both 208Pb and 48Ca have been precisely measured by the PREX and CREX experiments via the parity violating asymmetry in longitudinally polarized elastic electron-nucleus scattering. The advantage of these parity violating electron scattering measurements lies in the use of an electroweak probe to measure these quantities, significantly reducing uncertainties from theoretical interpretations. The PREX measurement of the large 208Pb nucleus, for which nuclear density functional theory can be applied, provides meaningful constraints on the density dependence of the symmetry energy of neutron-rich nuclear matter; an important parameter for the nuclear equation of state. The complimentary CREX measurement of the modestly sized, neutron rich 48Ca nucleus, for which edge effects are significant, provides an important benchmark for nuclear theory to help bridge ab-initio theoretical approaches and the nuclear density functional theory. While the electroweak nature of the interaction lends itself to a clean interpretation of the results it also presents significant experimental hurdles, including the need to employ innovative precision beam control techniques. This talk will give an overview experimental results from the PREX and CREX collaborations, will touch upon the tension observed between these results and select theoretical calculations and measurements, and will describe the techniques employed to meet the stringent systematic uncertainty goals arising from beam asymmetries during the PREX-II and CREX experiments. The upcoming MOLLER experiment which will utilize these beam control techniques to search for new BSM (Beyond the Standard Model) physics through ultra-precise measurement of the weak charge of the electron will also be discussed.

Relevant background with commentary from Speaker:

• What is the electroweak force?
• Asymmetric Insight: The SLAC E158 Experiment
• Just How Weak Is The Weak Force?: QWEAK
• There's also the heavy, long, MOLLER TDR (super detailed more than any student would want to read)