  Differential cross sections and photon-beam asymmetries for the gamma p ->
pi- Delta++(1232) reaction have been measured for 0.7<cos(theta)<1 and
Egamma=1.5-2.95 GeV at SPring-8/LEPS. The first-ever high statistics cross
section data are obtained in this kinematical region, and the asymmetry data
for 1.5<Egamma(GeV)<2.8 are obtained for the first time. This reaction has a
unique feature for studying the production mechanisms of a pure $u\bar{u}$
quark pair in the final state from the proton. Although there is no distinct
peak structure in the cross sections, a non-negligible excess over the
theoretical predictions is observed at Egamma=1.5-1.8 GeV. The asymmetries are
found to be negative in most of the present kinematical regions, suggesting the
dominance of pi-exchange in the t-channel. The negative asymmetries at forward
meson production angles are different from the asymmetries previously 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.
