The polarization of the recoil proton in the photoproduction process γ+p→p+π0 has been measured with the beam of the Frascati electrosynchrotron at an angle of 90° in the c.m. system, in the energy interval (500÷900) MeV. A counter technique has been used, and the polarization of the proton was revealed by the left to right asymmetry in the elastic scattering of the protons in a carbon target. The experimental results are given in Table III and in Fig. 10. A definite polarization is found, always of the same sign and equal to −0.4±.14, −0.63±.23, −0.6±.25, −0.57±.12, −0.38±.09, −0.5±.17, −0.5±.22 at the γ-ray energies of 560, 610, 650, 700, 750, 800, 850 MeV respectively. The discussion of these experimental results, together with the data of angular dstributions, allows to conclude that they are in agreement with the hypothesis that the second resonance is a transition (E 1,d 3/2) and the third one is a transition (E 2,f 3/2).
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We present a measurement of the polarization of Antilambda hyperons produced in nu_mu charged current interactions. The full data sample from the NOMAD experiment has been analyzed using the same V0 identification procedure and analysis method reported in a previous paper for the case of Lambda hyperons. The Antilambda polarization has been measured for the first time in a neutrino experiment. The polarization vector is found to be compatible with zero.
Lambdabar polarization in regions of Feynman X (XL).
Lambdabar polarization in regions of the Bjorken scaling variable X.
At the Bonn 2.5 GeV electron synchrotron the angular distribution of the target asymmetry T = (σ↑ − σ↓) (σ↑ + σ↓) for the reaction γp↑ → π + n was measured at a mean photon energy of 700 MeV and pion CM-angles from 50° to 155°. The combination of a 3 He-cryostat, polarizing the free protons in the target up to 65%, with a large acceptance magnet for pion detection led to statistical errors of the target asymmetry comparable with those of cross section measurements.
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We have measured the cross sections at 90° c.m. for π± and π0 photoproduction with polarized photons. The photon energies ranged from 0.8 to 2.2 GeV. We compare the resonant "bumps" in the cross section with theoretical models. The measured asymmetry agrees with a quark-model calculation though the predicted cross sections are low.
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