Differential cross section and photon-beam asymmetry for the gamma p -> pi- Delta++(1232) reaction at forward pi- angles for Egamma=1.5-2.95 GeV

Differential cross sections and photon-beam asymmetriesfor the gamma p -> pi- Delta++(1232) reaction have been measured for 0.7 SPring-8/LEPS. The first-ever high statistics cross section data are obtained in this kinematical region, and the asymmetrydata for 1.5 asymmetriesare found to be negative in most of the present kinematical regions, suggesting the dominance of pi-exchange in the t-channel. The negative asymmetriesat forward meson production angles are different from the asymmetriespreviously measured for the photoproduction reactions which produce a $d\bar{d}$ or an $s\bar{s}$ quark pair in the final state. Advanced theoretical models introducing nucleon resonances and additional unnatural parity exchanges are needed to reproduce the present data.