Deeply virtual and exclusive electroproduction of omega mesons

Journal Article · Fri Apr 01 04:00:00 EST 2005

OSTI ID:839446

Morand, L

The exclusive omega electroproduction off the proton was studied in a large kinematical domain above the nucleon resonance region and for the highest possible photon virtuality (Q{sup 2}) with the 5.75 GeV beam at CEBAF and the CLAS spectrometer. Cross sections were measured up to large values of the four-momentum transfer (-t < 2.7 GeV{sup 2}) to the proton. The contributions of the interference terms sigma{sub TT} and sigma{sub TL} to the cross sections, as well as an analysis of the omega spin density matrix, indicate that helicity is not conserved in this process. The t-channel pi{sup 0} exchange, or more generally the exchange of the associated Regge trajectory, seems to dominate the reaction {gamma}* p {yields} omega p, even for Q{sup 2} as large as 5 GeV{sub 2}. Contributions of handbag diagrams, related to Generalized Parton Distributions in the nucleon, are therefore difficult to extract for this process. Remarkably, the high-t behavior of the cross sections is nearly Q{sup 2}-independent, which may be interpreted as a coupling of the photon to a point-like object in this kinematical limit.

• Research Organization: Thomas Jefferson National Accelerator Facility, Newport News, VA (US)
• Sponsoring Organization: US Department of Energy; USDOE Office of Energy Research (ER) (US)
• DOE Contract Number: AC05-84ER40150
• OSTI ID: 839446
• Report Number(s): JLAB-PHY-05-326; DOE/ER/40150-3346; hep-ex/0504057
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CROSS SECTIONS
DENSITY MATRIX
ELECTROPRODUCTION
HELICITY
MESONS
NUCLEONS
PARTONS
PHOTONS
PROTONS
RESONANCE
SPIN
T CHANNEL