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International Nuclear Physics Conference, INPC 2007, Tokyo : Japon (2007)
Deeply Virtual Compton Scattering and deep neutral pion production in Hall A at Jefferson Laboratory
P.Y. Bertin1
DVCS, HALL A Collaboration(s)

Electro-production of a photon is the simplest way to access the Generalised PartonDistributions (GPD) through Deeply Virtual Compton Scattering (DVCS) which interfereswith the Bethe-Heitler (BH) process. DVCS experiments on the proton and on the neutron using a longitudinally polarized 5.75GeV electron beam in Hall A at JLab will be described. The exclusivity of the reactionwas ascertained using the missing-mass technique of the recoil nucleon and by substactingπ0 contamination. The helicity-dependent cross-section difference at the Q2 = 2.3, 1.9 and 1.5 GeV2 and the unpolarized cross section at Q2 = 2.3 GeV2 on the proton at xBj.= 0.36 willbe presented. A scaling test of DVCS based on the formalism of Compton form factors was obtained from the cross-section difference. The influence of the pure DVCS2 terms in theunpolarized cross section was found to be important. We will describe how to isolate the DVCS2 term from the BH-DVCS interference in a new experiment . A model-dependentconstraint on the quark angular momentum was deduced from the DVCS neutron data. The four polarized π0 electro-production cross sections dσΤ + ε dσL , dσΤΤ, dσLT and dσLT' have been extracted at Q2 = 2.3 GeV2/c2 on the proton at xBj.= 0.36 . A comparison withthe available models will be given. I will present also an overview of the DVCS program in the Hall A for the Jlab 12 GeV upgrade.
1 :  LPC - Laboratoire de Physique Corpusculaire [Clermont-Ferrand]
Physique/Physique Nucléaire Expérimentale