Parity violation in pion electroproduction and photoproduction with a proton target |
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Authors: | Sai-Ping Li EM Henley W-YP Hwang |
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Institution: | Institute for Nuclear Theory, Department of Physics, FM-15, University of Washington, Seattle, Washington 98195 USA |
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Abstract: | Parity violation in pion electroproduction and photoproduction on a proton target is investigated as a possible means of elucidating the structure of the electronic and non-leptonic neutral weak currents. We calculate both parity-violating effects caused directly by Z-boson exchange, which contributes only to electron scattering, and those due to parity-violating electromagnetic and nuclear interactions. The asymmetry in electroproduction is of order 20?5, whereas that in photoproduction is ~10?7. The sensitivity to the parameter sin2θw is investigated; it is a maximum at backward electron scattering angles. In addition to the Born terms, contributions from the Δ(1232) resonance and the light vector mesons ?(776) and ω(782)] are included in the model. Fits to the observed π0 and π+ electroproduction and photoproduction cross sections indicate that the model accounts for the production data in the medium energy region. |
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