[Clas12_deepana] Re : [EXTERNAL] Abstract for APS

[Pierre Chatagnon]

Hello Volker, 

Yes the initial photon is circularly polarized (and its polarization is function of the helicity of the beam). The TCS cross section depends on this initial polarization (as DVCS depends on the beam helicity) and the associated assymetry is dependent on the imagninary part CFF H. Note that I correct for the polarization transfer calculable from QED. 

Regards 
Pierre 

-----Mail original----- 
De: "Volker Burkert" <burkert at jlab.org> 
À: "Pierre Chatagnon" <chatagnon at ipno.in2p3.fr> 
Cc: "CLAS12 Deep Process Analysis" <clas12_deepana at jlab.org>, "Marco Contalbrigo" <mcontalb at fe.infn.it> 
Envoyé: Mardi, Janvier 5, 2021 03:57:09 PM 
Objet: Re: [Clas12_deepana] [EXTERNAL] Abstract for APS 

Dear Pierre, 
Could you clarify one aspect in the abstract. 

You are talking about the photon polarization that you will show and compare to models. 
I am confused about this. 
You start with a polarized electron beam, and the interaction with the proton is therefore through 
a circularly polarized photon. But that is just a QED process and precisely calculable. 
When you refer to photon polarization, do you mean the time-like photon decaying to e+e-? 
If that is so, you may want to rephrase the corresponding sentence in the abstract. 

Otherwise it is a nice abstract. 

Best regards, 
Volker 

> On Jan 5, 2021, at 8:56 AM, Pierre Chatagnon <chatagnon at ipno.in2p3.fr> wrote: 
> 
> <APS2021.odt>