Electroproduction of pi exp 0 -Mesons on Protons at W = Sqrt (Q+p) exp 2 = 1400-2000 MeV, Vertical Stroke Q exp 2 Vertical Stroke = Vertical Stroke (E-E') exp 2 Vertical Stroke Approx. Equal to 0.01-0.1 GeV exp 2 , and Vertical St

摘要

The electroproduction of pi exp 0 -mesons on protons has been measured with electrons of 1.7 and 2.1 GeV energy in the region of the nucleon resonances at W = sqrt (q+p) exp 2 = 1400-2000 MeV at rather low values of vertical stroke q exp 2 vertical stroke vertical stroke (e-e') exp 2 vertical stroke = 0.01-0.1 GeV exp 2 but at high values of the nucleon recoil vertical stroke t vertical stroke = vertical stroke (p-p') exp 2 vertical stroke approx. equal to 0.6-2.2 GeV exp 2 corresponding to THETA sup(cm)sub( pi ) approx. equal to 145 exp 0 -180 exp 0 . Up to W approx. equal to 1650 MeV the cross section for pi exp 0 -production with virtual photons of vertical stroke q exp 2 vertical stroke approx. equal to 0.03 GeV exp 2 is only slightly smaller than that with real photons. For W >= 1700 MeV the cross section at vertical stroke q exp 2 vertical stroke approx. equal to 0.03 GeV exp 2 is on average a factor of 2 smaller than that at q exp 2 = 0 but only slightly higher than that at vertical stroke q exp 2 vertical stroke approx. equal to 0.3-1 GeV exp 2 . (ERA citation 08:037629)