Single Pion Electroproduction in the Delta(1232) Resonance from CLAS Data at Jefferson Lab
Electroproduction of the Delta(1232) is a large component of a program at Jefferson Lab to study the Q{sup 2} evolution of the gammaNN* vertex for many of the low-lying nucleon resonances. Single pion electroproduction of the Delta provides information which is sensitive to models describing the internal motion of baryon constituents. Three multipoles contribute to the gamma*N -> transition: the electric, magnetic and scalar/longitudinal multipoles E1+, M1+ and S1+. At low Q{sup 2}, the focus has been on incorporating relativistic effects into the constituent quark model (CQM) as well as contributions from pion cloud and one gluon exchange. At higher Q{sup 2}, where the short distance behavior of the quark-gluon confining interaction is probed, QCD sum rule calculations, valence QCD and perturbative QCD (pQCD) have been employed. New measurements of the electroproduction of the Delta(1232) resonance through the p(e, e'p)pi{sup o} and p(e, e'pi+)n reactions have been performed. The data were taken with the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab using incident electron energies of 1.645, 2.445 and 4.045 GeV. Elastic and inelastic cross sections were measured simultaneously with continuous coverage over a large range of four-momentum transfer Q{sup 2}=(0.3-4.0 GeV{sup 2}). Decay angular distributions in the piN center-of-mass were obtained over the full range of COS Thetac.m. and øc.m. The high statistical accuracy of this data set is expected to provide strong constraints on dynamic models of the N -> Delta transition form factors. A preliminary partial wave analysis will be presented.
- Research Organization:
- Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC05-84ER40150
- OSTI ID:
- 793198
- Report Number(s):
- JLAB-PHY-98-13; DOE/ER/40150-2049; TRN: US0200965
- Journal Information:
- Few Body Syst.Suppl., Vol. 11; Other Information: contribution to Joint ECT* / TJNAF Workshop On N* Physics And Nonperturbative QCD, May 1998, Trento; PBD: 1 May 1999
- Country of Publication:
- United States
- Language:
- English
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