Photopion Physics at MAMI

Mon., Nov. 7, 2016 3:30 p.m. - Mon., Nov. 7, 2016 4:30 p.m.

Location: CK 187

Abstract: Recent measurements and future plans for photopion experiments with the CB-TAPS detector system in the A2 hall at the Mainzer Microtron will be presented. First, a measurement with linearly polarized photons and an unpolarized liquid- hydrogen target will be discussed. The beam asymmetry along with differential cross sections provide the most stringent test to date of the predictions of Chiral Perturbation Theory and its energy region of convergence1. Second, a more recent measurement was performed using both circularly polarized photons and a transversely polarized butanol frozen-spin target to extract the polarization-dependent differential cross section associated with the target asymmetry2. Results from both measurements have been used for a model independent determination of S- and P- wave multipoles in the π0 threshold region, which includes for the first time a direct determination of the imaginary part of the E0+ multipole. Finally, plans for a novel π0 photoproduction measurement on 3He to obtain the elusive E0+ multipole for the neutron channel will be introduced.

Speaker: David Hornidge is a Professor in the Dept. of Physics at Mount Allison University. He is also a member of the Royal Society of Canada College of New Scholars, Artists, and Scientist.