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) amplitud...

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Veröffentlicht in:	Physical review letters 2001-04, Vol.86 (14), p.2963-2966
Hauptverfasser:	Mertz, C, Vellidis, C E, Alarcon, R, Barkhuff, D H, Bernstein, A M, Bertozzi, W, Burkert, V, Chen, J, Comfort, J R, Dodson, G, Dolfini, S, Dow, K, Farkhondeh, M, Finn, J M, Gilad, S, Gothe, R W, Jiang, X, Joo, K, Kaloskamis, N I, Karabarbounis, A, Kelly, J J, Kowalski, S, Kunz, C, Lourie, R W, McIntyre, J I, Milbrath, B D, Miskimen, R, Mitchell, J H, Papanicolas, C N, Perdrisat, C F, Sarty, A J, Shaw, J, Soong, S B, Tieger, D, Tschalaer, C, Turchinetz, W, Ulmer, P E, Van Verst, S, Warren, G A, Weinstein, L B, Williamson, S, Woo, R J, Young, A
Format:	Artikel
Sprache:	eng
Schlagworte:	AMPLITUDES DELTA-1232 BARYONS ELECTROPRODUCTION EXCITATION MATHEMATICAL MODELS PHYSICS OF ELEMENTARY PARTICLES AND FIELDS QUADRUPOLES
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Beschreibung
Zusammenfassung:	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.
ISSN:	0031-9007 1079-7114
DOI:	10.1103/PhysRevLett.86.2963