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Beam-helicity asymmetry in photon and pion electroproduction in the Δ(1232)-resonance region at Q2 = 0.35(GeV/c)2

Authors :
Bensafa, I.K.
Achenbach, P.
Ases Antelo, M.
Ayerbe, C.
Baumann, D.
Böhm, R.
Bosnar, Damir
Burtin, E.
Defa&#255
D'Hose, N.
Ding, M.
Distler, M.O.
Doria, L.
Fonvieille, H.
Friedrich, J.M.
Friedrich, J.
Garcia Llongo, J.
Janssens, P.
Jover Manas, G.
Kohl, M.
Laveissiere, G.
Lloyd, M.
Makek, Mihael
Marroncle, J.
Merkel, H.
Merle, P.
Müller, U.
Nungesser, L.
Pasquini, B.
Perez Benito, R.
Pochodzalla, J.
Potokar, M.
Rosner, G.
Sanchez Majos, S.
Seimetz, M.
Sirca, S.
Spitzenberg, T.
Tamas, G.
Van de Vyver, R.
Van Hoorebeke, L.
Walcher, Th.
Weis M.
Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC)
Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS)
Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (DAPNIA)
Commissariat à l'énergie atomique et aux énergies alternatives (CEA)
MAMI-A1
Source :
European Physical Journal A, European Physical Journal A, 2007, 32, pp.69-75. ⟨10.1140/epja/i2006-10277-3⟩, European Physical Journal A, EDP Sciences, 2007, 32, pp.69-75. ⟨10.1140/epja/i2006-10277-3⟩
Publication Year :
2007
Publisher :
Springer Science and Business Media LLC, 2007.

Abstract

The beam-helicity asymmetry has been measured simultaneously for the reactions (e p \to e p \gamma) and (e p \to e p \pi^0) in the $\Delta (1232)$ resonance region at $Q^2=$ 0.35 (GeV/c)$^2$. The experiment was performed at MAMI with a longitudinally polarized beam and an out-of-plane detection of the proton. The results are compared with calculations based on Dispersion Relations for virtual Compton scattering and with the MAID model for pion electroproduction. There is an overall good agreement between experiment and theoretical calculations. The remaining discrepancies may be ascribed to an imperfect parametrization of some $\gamma^{(*)} N \to \pi N$ multipoles, mainly contributing to the non-resonant background. The beam-helicity asymmetry in both channels ($\gamma$ and $\pi^0$) shows a good sensitivity to these multipoles and should allow future improvement in their parametrization.<br />Comment: 7 pages, 8 figures, version to appear in EPJA

Details

ISSN :
1434601X and 14346001
Volume :
32
Database :
OpenAIRE
Journal :
The European Physical Journal A
Accession number :
edsair.doi.dedup.....55559aec4dcb92e56322870bbfe7f6dc
Full Text :
https://doi.org/10.1140/epja/i2006-10277-3