[Deeppwg] DVCS abstract for DIS19 by Francesco Bossu

[Marco Contalbrigo]

Dear all,
below is a DVCS abstract Francesco intends to submit to
DIS19. If you have suggestions, they are welcome.
Best regards, Marco.


First data on Deeply Virtual Compton Scattering with CLAS12
at 10.6 GeV Electron Beam

Generalized Parton Distributions (GPDs) provide the opportunity to obtain a 
3-dimensional description of a nucleon in terms of its constituent partons. 
Moreover, GPDs are related, via QCD-based sum rules, to total angular momentum, 
mass and pressure distributions inside the nucleon. GPDs are experimentally 
accessible via the deeply virtual Compton scattering (DVCS), i.e. the 
absorption of a highly virtual photon by the proton and the subsequent emission 
of a high-energy photon.

At Jefferson Lab, the brand new CLAS12 spectrometer has been commissioned and 
has collected its first DVCS data with a 10.6 GeV continuous electron beam in 
winter 2017 - spring 2018. Its central part, containing the cylindrical silicon 
and micromegas trackers within a 5T-solenoidal field surrounding the liquid 
hydrogen target, is ideal to detect the recoil proton of a DVCS event. The 
forward detectors, placed in a toroidal magnetic field, detect the associated 
scattered electron and high energy photon. A first look at the data collected 
so far with CLAS12 for DVCS studies on unpolarized proton target will be 
presented together with projections for the full run.