[PAST EVENT] Physics Colloquium - Elton Smith
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- Open to the public
Elton Smith, Jefferson Lab, Title of talk: "Can you stretch a pion?"
Electromagnetic polarizabilities are fundamental properties of composite systems such as molecules, atoms, nuclei and hadrons. They measure how easy it is to stretch a system using electromagnetic forces. Hadrons, such as nucleons and pions, are extremely stiff, which means that deformations are very small and difficult to measure precisely. However, pion polarizabilites are rigorous predictions of Chiral Perturbation Theory in the chiral limit and therefore represent desirable targets for exploration. We will describe two experiments in Hall D at Jefferson Lab that utilize a new technique to measure pion polarizabilities, the Primakoff photo-production of charged and neutral pion pairs using linearly polarized 6 GeV photons on a 208Pb target. The experimental run was completed in summer of 2022, and we will present a first look at the data.