Electroproduction of {Delta}(1232) resonance at high momentum transfer

Journal Article · Fri May 01 04:00:00 EDT 1998 · AIP Conference Proceedings

OSTI ID:647293

Jefferson Lab experiment E94-014 measured the the excitation of the {Delta}(1232) resonance at Q{sup 2} near 2.8 and 4 Gev{sup 2}/c{sup 2} via the reaction p(e,e{sup {prime}}p){pi}{sup 0}. This is the highest Q{sup 2} for which exclusive resonance electroproduction has ever been observed. Decay distributions of the {Delta}(1232) resonance into the p{pi}{sup 0} final state were measured over a wide range of barycentric decay angles and energies. The goal of this experiment is to asses the transition in Q{sup 2} from the constituent quark model (CQM) to the regime where hard processes become important. At Q{sup 2}{approximately}fewthinspGeV{sup 2}/c{sup 2} the ratio E{sub 1+}/M{sub 1+} depends dramatically on the theoretical description, varying from a few 10{sup {minus}2} in the CQM limit, to about 1 in the pQCD limit. Preliminary analysis of the data shows that the ratio E{sub 1+}/M{sub 1+} remains small at Q{sup 2} up to 4 Gev{sup 2}/c{sup 2}. After first pass analysis we obtain E{sub 1+}/M{sub 1+}={minus}4.1{plus_minus}1.2{percent} at Q{sup 2}=2.8thinspGev{sup 2}/c{sup 2} and E{sub 1+}/M{sub 1+}={minus}7.9{plus_minus}0.8{percent} at Q{sup 2}=4thinspGev{sup 2}/c{sup 2} (statistical errors only). {copyright} {ital 1998 American Institute of Physics.}

• OSTI ID: 647293
• Report Number(s): CONF-970842--
• Journal Information: AIP Conference Proceedings, Journal Name: AIP Conference Proceedings Journal Issue: 1 Vol. 432; ISSN APCPCS; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
CROSS SECTIONS
DELTA BARYONS
DELTA-1232 BARYONS
ELECTRON-PROTON INTERACTIONS
ELECTRONS
ELECTROPRODUCTION
EXCLUSIVE INTERACTIONS
MASS SPECTRA
PIONS
PIONS NEUTRAL
PROTONS