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Title: gamma* N --> Delta at JLab: Exploring the High Q2 Regime

Abstract

We report a new measurement of the exclusive electroproduction reaction gamma* p --> pi0 p to explore the evolution from soft non-perturbative physics to hard processes via the Q2 dependence of the magnetic (M1+), electric (E1+) and scalar (S1+) multipoles in the N --> Delta transition. 9000 differential cross section data points cover W from threshold to 1.4 GeV/c2, 4pi center-of-mass solid angle, and Q2 from 3 to 6 GeV2/c2, the highest yet achieved. It is found that the magnetic form factor G M * decreases with Q2 more steeply than the proton magnetic form factor, the ratio E1+/M1+ is small and negative, indicating strong helicity non-conservation, and the ratio S1+/M1+ is negative, while its magnitude increases with Q2.

Authors:
; ;
Publication Date:
Research Org.:
Thomas Jefferson National Accelerator Facility, Newport News, VA
Sponsoring Org.:
USDOE - Office of Energy Research (ER)
OSTI Identifier:
910569
Report Number(s):
JLAB-PHY-07-684; DOE/ER/40150-4296
Journal ID: ISSN 0094-243X; APCPCS; TRN: US0704259
DOE Contract Number:  
AC05-84ER40150
Resource Type:
Conference
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 904; Conference: Workshop on the Shape of Hadrons, 27-29 Apr 2006, Athens, Greece
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; DIFFERENTIAL CROSS SECTIONS; ELECTROPRODUCTION; FORM FACTORS; HADRONS; HELICITY; MULTIPOLES; PHYSICS; PROTONS; SCALARS; SHAPE

Citation Formats

Maurizio Ungaro, Kyungseon Jo, and Paul Stoler. gamma* N --> Delta at JLab: Exploring the High Q2 Regime. United States: N. p., 2007. Web. doi:10.1063/1.2734308.
Maurizio Ungaro, Kyungseon Jo, & Paul Stoler. gamma* N --> Delta at JLab: Exploring the High Q2 Regime. United States. doi:10.1063/1.2734308.
Maurizio Ungaro, Kyungseon Jo, and Paul Stoler. Sun . "gamma* N --> Delta at JLab: Exploring the High Q2 Regime". United States. doi:10.1063/1.2734308. https://www.osti.gov/servlets/purl/910569.
@article{osti_910569,
title = {gamma* N --> Delta at JLab: Exploring the High Q2 Regime},
author = {Maurizio Ungaro and Kyungseon Jo and Paul Stoler},
abstractNote = {We report a new measurement of the exclusive electroproduction reaction gamma* p --> pi0 p to explore the evolution from soft non-perturbative physics to hard processes via the Q2 dependence of the magnetic (M1+), electric (E1+) and scalar (S1+) multipoles in the N --> Delta transition. 9000 differential cross section data points cover W from threshold to 1.4 GeV/c2, 4pi center-of-mass solid angle, and Q2 from 3 to 6 GeV2/c2, the highest yet achieved. It is found that the magnetic form factor GM* decreases with Q2 more steeply than the proton magnetic form factor, the ratio E1+/M1+ is small and negative, indicating strong helicity non-conservation, and the ratio S1+/M1+ is negative, while its magnitude increases with Q2.},
doi = {10.1063/1.2734308},
journal = {AIP Conference Proceedings},
number = ,
volume = 904,
place = {United States},
year = {Sun Apr 01 00:00:00 EDT 2007},
month = {Sun Apr 01 00:00:00 EDT 2007}
}

Conference:
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