Search for quadrupole strength in the electroexcitation of the delta+(1232)

C Mertz; C E Vellidis; R Alarcon; D H Barkhuff; A M Bernstein; W Bertozzi; V Burkert; J Chen; J R Comfort; G Dodson; S Dolfini; K Dow; M Farkhondeh; J M Finn; S Gilad; R W Gothe; X Jiang; K Joo; N I Kaloskamis; A Karabarbounis; J J Kelly; S Kowalski; C Kunz; R W Lourie; J I McIntyre; B D Milbrath; R Miskimen; J H Mitchell; C N Papanicolas; C F Perdrisat; A J Sarty; J Shaw; S B Soong; D Tieger; C Tschalaer; W Turchinetz; P E Ulmer; S Van Verst; G A Warren; L B Weinstein; S Williamson; R J Woo; A Young

doi:10.1103/PhysRevLett.86.2963

Search for quadrupole strength in the electroexcitation of the delta+(1232)

Phys Rev Lett. 2001 Apr 2;86(14):2963-6. doi: 10.1103/PhysRevLett.86.2963.

Affiliation

¹ Department of Physics and Astronomy, Arizona State University, tempe 85287, USA.

PMID: 11290083
DOI: 10.1103/PhysRevLett.86.2963

Abstract

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.