The γp→π0p reaction was studied at laboratory photon energies from 425 to 1445 MeV with a transversely polarized target and a longitudinally polarized beam. The beam-target asymmetry F was measured for the first time and new high precision data for the target asymmetry T were obtained. The experiment was performed at the photon tagging facility of the Mainz Microtron (MAMI) using the Crystal Ball and TAPS photon spectrometers. The polarized cross sections were expanded in terms of associated Legendre functions and compared to recent predictions from several partial-wave analyses. The impact of the new data on our understanding of the underlying partial-wave amplitudes and baryon resonance contributions is discussed.
Target asymmetry T for c.m. energy W= 1.3062 GeV
Target asymmetry T for c.m. energy W= 1.3275 GeV
Target asymmetry T for c.m. energy W= 1.3486 GeV
The asymmetry A = (σ + −σ − ) (σ + +σ − ) of the reaction γ p↑↓ → π 0 p was measured at the Deutsches Elektronen Synchrotron DESY, Hamburg at a mean photon energy of 4.0 GeV in the four-momentum transfer range 0.2 (GeV/ c ) 2 ⩽ −t ⩽ 1.1 (GeV/ c ) 2 in steps of approximately 0.08 (GeV/ c ) 2 . The π 0 -meson and the proton were detected in coincidence. The asymmetry is compatible with zero in the t -range 0.2 (GeV/ c ) 2 ⩽ − t ⩽ 0.4 (GeV/ c ) 2 and negative in the t -range ⩾ 0.5 (GeV/ c ) 2 .
No description provided.
The cross section for photoproduction of π0 mesons was measured at a photon energy of 3 GeV and squared four-momentum transfer (t) of -0.1 to -1.2 (GeV/c)2 using plane-polarized photons. The asymmetry was found to be consistent with +1.0 for t values above -0.4 and below -1.1. For −0.4<~t<~−1.0 there is a dip in the asymmetry and at t=−0.6 it drops to 0.55 ± 0.15. This result precludes a simple Regge model with ω0 and B; a theoretical description requires Regge cuts or an ω′ exchange.
No description provided.
MIT PREP (1967).
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