Search for quadrupole strength in the electroexcitation of the delta+(1232).
High-precision 1H(e,e'p)pi(0) measurements at Q2 = 0.126 (GeV/c)2 are reported, which allow the determination of quadrupole amplitudes in the gamma*N-->Delta transition; they simultaneously test the reliability of electroproduction models. The derived quadrupole-to-dipole ( I = 3/2) amplitude ratios, R(SM) = (-6.5+/-0.2(stat+sys)+/-2.5(mod))% and R(EM) = (-2.1+/-0.2(stat+sys)+/-2.0(mod))%, are dominated by model error. Previous R(SM) and R(EM) results should be reconsidered after the model uncertainties associated with the method of their extraction are taken into account.
Mertz
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C
Department of Physics and Astronomy, Arizona State University, tempe 85287, USA.
Vellidis
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Alarcon
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Barkhuff
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Bernstein
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Bertozzi
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Burkert
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Chen
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Comfort
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Dodson
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Dolfini
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Dow
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Farkhondeh
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Finn
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Gilad
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Gothe
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Jiang
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Joo
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Kaloskamis
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Karabarbounis
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Kelly
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Kowalski
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Kunz
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Lourie
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McIntyre
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Milbrath
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Miskimen
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Mitchell
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Papanicolas
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Perdrisat
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Sarty
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Shaw
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Soong
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Tieger
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Tschalaer
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Turchinetz
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Ulmer
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Van Verst
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Warren
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Weinstein
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Williamson
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Woo
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Young
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