Measurement of the beam-helicity asymmetry in the p((-->)e,e'p)pi(0) reaction at the energy of the Delta(1232) resonance.

In a p((-->)e,e'p)pi(0) out-of-plane coincidence experiment at the three-spectrometer setup of the Mainz Microtron MAMI, the beam-helicity asymmetry has been precisely measured around the energy of the Delta(1232) resonance and Q(2) = 0.2(GeV/c)(2). The results are in disagreement with three up-to-date model calculations.

Neutral pion threshold production at Q(2) = 0.05 GeV(2)/c(2) and chiral perturbation theory.

New data are presented on the p(e,e'p)pi(0) reaction at threshold at a four-momentum transfer of Q(2) = 0.05 GeV(2)/c(2). The data were taken with the three-spectrometer setup of the A1 Collaboration at the Mainz Microtron MAMI.

Measurement of the recoil polarization in the p(e-->, e'p-->)pi(0) reaction at the Delta(1232) resonance.

The recoil proton polarization has been measured in the p(e-->,e'p-->)pi(0) reaction in parallel kinematics around W = 1232 MeV, Q2 = 0.121 (GeV/c)2, and epsilon = 0.718 using the polarized cw electron beam of the Mainz Microtron.