[Sbs] Abstract DDVCS

[Alexandre Camsonne]

Ok here is the final version after some comment from Ole :

The Generalized Parton
Distributions (GPDs) are a more general formalism
encompassing the concept of elastic form factor (FF) and parton
distributions (PDFs) introducing a third independent variable called
skewdness xi in addition to usual x\textunderscore bj and t variables which
are defined for the PDFs. Those distributions thus contain more information
than the FF and PDFs allowing to give a more spatial and dynamical
description of the nucleon. To measure GPDs one has to measure exclusive
reaction. The simplest exclusive reaction is the exclusive production of
photons or Deeply Virtual Compton Scattering. One drawback of this
measurement is that the real photon constrains the measurement of the GPDs
to the line xi$=$x. The Doubly Virtual Compton Scattering (DDVCS) is the
similar process involving a virtual photon in the final state. This virtual
photon decays into a dilepton pair allowing some values of xi different
than
x\textunderscore bj. High luminosity is required since cross sections are
smaller by a factor 100. I will present how the SuperBigBite spectrometer
could be used to measure the DDVCS process particularly in the dimuon
channel.

Alexandre


On Mon, Jul 1, 2013 at 10:15 AM, Alexandre Camsonne <camsonne at jlab.org>wrote:

> Hello,
>
> here is the abstract for Double DVCS. I might remove it if I figure out
> the acceptance is not large enough to make an interesting measurement.
>
> Alexandre Camsonne for the Hall A SuperBigBite Collaboration
>
> Double Deeply Virtual Compton Scattering in Hall A using SuperBigBite
> Spectrometer
>
> The Generalized Parton Distributions (GPDs) are a more general formalism
> englobing the concept of elastic form factor (FF) and parton distributions
> (PDFs) introducing a third independent variable called skewdness xi in
> addition to usual x_bj and t variables which are define for the PDFs. Those
> distributions thus contain more informations than the FF and PDFs allowing
> to give a more spatial and dynamical description of the nucleon. To measure
> GPDs one has to measure exclusive reaction. The simpliest exclusive
> reaction is the exclusive production of photons or Deeply Virtual Compton
> Scattering. One drawback of this measurement is that the real photon
> constrains the measurement of the GPDs to the line xi=x. The Doubly Virtual
> Compton Scattering (DDVCS) is the similar process involving a virtual
> photon in the final state. This virtual photon decays into a dilepton pair
> allowing some values of xi different than x_bj. High luminosity is required
> since cross sections are smaller by a factor 100. I will present an idea
> using the SuperBigBite Spectrometer to try to measure the DDVCS
> particularly in the dimuon channel.
>
> Alexandre
>
>
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