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We calculate the neutral pion photoproduction on the proton near threshold in covariant baryon chiral perturbation theory, including the $Delta(1232)$ resonance as an explicit degree of freedom, up to chiral order $p^{7/2}$ in the $delta$ counting. We compare our results with recent low-energy data from the Mainz Microtron for angular distributions and photon asymmetries. The convergence of the chiral series of the covariant approach is found to improve substantially with the inclusion of the $Delta(1232)$ resonance.
The recoil proton polarization has been measured in the p (vec e,evec p) pi^0 reaction in parallel kinematics around W = 1232 MeV, Q^2 = 0.121 (GeV/c)^2 and epsilon = 0.718 using the polarized c.w. electron beam of the Mainz Microtron. Due to the spi
The first measurement of the helicity dependence of the photoproduction cross section of single neutral pions off protons is reported for photon energies from 600 to 2300,MeV, covering nearly the full solid angle. The data are compared to predictions
We report new p$(vec{e},e^prime p)pi^circ$ measurements in the $Delta^{+}(1232)$ resonance at the low momentum transfer region utilizing the magnetic spectrometers of the A1 Collaboration at MAMI. The mesonic cloud dynamics are predicted to be domina
The reaction p(e,ep)pi^0 has been studied at Q^2=0.2 (GeV/c)^2 in the region of W=1232 MeV. From measurements left and right of q, cross section asymmetries rho_LT have been obtained in forward kinematics rho_LT(theta_pi^0=20deg) = (-11.68 +/- 2.36_s
The reaction $gamma p to pi^circ gamma^prime p$ has been measured with the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI for energies between $sqrt{s}$ = 1221--1331 MeV. Cross sections differential in angle and energy have been de