[Clas12_first_exp] [EXTERNAL] RE:PAC48 slides

[Volker Burkert]

One comment I have re Markus Diehl's contribution.

He demonstrated that the D-term can be extracted from the subtracted dispersion relation (maybe we should add that reference to this paper). This can only be applied by integrating over the entire \xi range. This requires a parameterization that is needed to do the integration as long as high x and very low x results are unavailable.
Kresemir's paper demonstrated that NN is just not constraint enough to extract the D-term.
So, it is a question of how to estimate the systematic uncertainties of the parameterization.

Volker



________________________________
From: Clas12_first_exp <clas12_first_exp-bounces at jlab.org> on behalf of Francois-Xavier Girod <fxgirod at jlab.org>
Sent: Thursday, September 24, 2020 11:55 AM
To: Latifa Elouadrhiri <latifa at jlab.org>
Cc: clas12_first_exp at jlab.org <clas12_first_exp at jlab.org>
Subject: Re: [Clas12_first_exp] [EXTERNAL] RE:PAC48 slides

Concerning Kresimir's article raised by Franck
This is indeed one of the best arguments we have to argue for more data, as I already said during the meeting several times

Kresimir's criticism is that we use ad-hoc functional forms to perform global fits, and that these include poorly constrained extrapolations
Kresimir's approach, performing neural network fits, provide on of the safest most conservative estimation of the D term uncertainties
Our strategy is diametrically opposite to his
To justify our strategy we need the fullest possible coverage in xB (the variable that requires extrapolation)

Also note that combining RGA and RGK data we will be able to cleanly separate the linear interference term from the DVCS^2 contribution

Best regards
FX

On Thu, Sep 24, 2020 at 3:54 PM SABATIE Franck <Franck.Sabatie at cea.fr<mailto:Franck.Sabatie at cea.fr>> wrote:
Dear Latifa,

It looks good, once you incorporate the official DVCS plots in the presentation.

Note that there is a significant risk Markus Diehl will comment about the article from K. Kumericki (Nature volume 570, pages E1–E2 (2019)) in response to your own Nature article: a convincing answer needs to be ready since you put it as an highlight.

Kind regards,
Franck


________________________________
De : Clas12_first_exp [clas12_first_exp-bounces at jlab.org<mailto:clas12_first_exp-bounces at jlab.org>] de la part de Latifa Elouadrhiri [latifa at jlab.org<mailto:latifa at jlab.org>]
Envoyé : jeudi 24 septembre 2020 14:40
À : clas12_first_exp at jlab.org<mailto:clas12_first_exp at jlab.org>
Objet : [Clas12_first_exp] PAC48 slides

Dear All,

I have posted the PAC48 RGA talk at clas12 doc-db. I have implemented all the comments I received from the dry run.

I am waiting for the final DVCS slide from Maxime/FX
I am also waiting to see if there better graphs/results from MesonX.

Victor please check the summary see if I captured your comment correctly.

Please let me know if you have any last comment/suggestion.

Best regards,

Latifa
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