ΔProduction Viaγp→Δπby Linearly Polarized Photons at 2.8 and 4.7 GeV

Abstract

The production of $\Delta \mathrm{}\left(1236\right)\mathrm{}$ by linearly polarized photons at 2.8 and 4.7 GeV was studied using a hydrogen bubble chamber. At 2.8 GeV the cross sections for $\gamma p\to {\Delta }^{++}{\pi }^{-}(\gamma p\to {\Delta }^0{\pi }^{+},{\Delta }^0\to p{\pi }^{-})$ were found to be 3.7 ± 0.4 μb (0.5 ± 0.2 μb); at 4.7 GeV, 1.0 ± 0.1 μb (0.16 ± 0.09 μb). Measurement of the parity asymmetry, $P_{\sigma }$, for ${\Delta }^{++}$ production with $\mathrm{}\left|t\right|<0.5\mathrm{}$ Ge${\mathrm{V}}^2$ yielded the values -0.27 ± 0.12 and -0.53 ± 0.15 at 2.8 and 4.7 GeV, respectively, whereas pure one-pion exchange would lead to $P_{\sigma }=-1\mathrm{}$.