[Clas12_dileptons] [EXTERNAL] Re: Vector meson production on nuclear targets

Sun Sep 7 09:29:29 EDT 2025

Hi,

I am currently on my way to the Low-x workshop in Croatia and won’t be able to join on Tuesday, but I have a question.

Yordanka recently put a student on coherent J/psi on deuterium as part of E12-11-003B in RGB. There is absolutely no problem in including this in the CAA. However, since this is a channel with very low statistics, perhaps at the end of the day we may consider trying to add up all available data?

Best,

Pawel

On Sep 5, 2025, at 11:08 PM, Stepan Stepanyan via Clas12_dileptons <clas12_dileptons at jlab.org> wrote:

Hi Richard and Pierre,

Thanks for drafting the CAA. I have a couple of questions, proposals.

I do not understand the comment about the EMC effect; we cannot do it. I also don't understand the comment about nucleon structure modification in the Hall D measurement. The subthreshold production indicates high-momentum nucleons, but it does not necessarily need to have a modified structure for these nucleons.
We should add the extraction of the J/psi N scattering cross section, as we wrote in the proposal for RG-B https://www.jlab.org/exp_prog/proposals/18/E12-11-003B.pdf .
I also propose to include coherent J/psi production on deuterium in the list of final states to study the gluonic structure of the deuteron.

Regards,
Stepan

On Sep 5, 2025, at 4:03 PM, Bryan McKinnon via Clas12_dileptons <clas12_dileptons at jlab.org> wrote:

Dear Pierre, Richard

This is a nice piece of work. Could you please add my name.

You’ve made the case clearly and concisely and what you have presented is definitely worthy of further formal investigations.

There are some formatting issues with the document and references. The figures often appear awkwardly in the middle of bulleted lists or between equation definitions.In the references "et al" appears at times between the author initials and surname rather than afterwards. Need to decide and apply the maximum number of authors before you use “et al” if you use it at all. Also the “j” in J/psi should be “J”.

Cheers
Bryan

On 5 Sep 2025, at 20:16, Pierre Chatagnon via Clas12_dileptons <clas12_dileptons at jlab.org> wrote:

Dear all,

We have been putting a CAA together with the goal to measure VM production on nuclear targets. Especially we are aiming to measure JPsi photoproduction and Phi electro production on all targets in RGD and RGE.

The draft of the CAA is attached to the mail.
If you'd like to sign it, please let us know and we will add your name to the list.
If you have any comments on the documents, please let us know also.

The CAA will be presented at the RGD meeting next week, so we plan to submit it by the end of next week to the Nuclear Working Group.

Cheers,
Pierre & Richard<CAA_Nuclear_JPsi.pdf>_______________________________________________
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___________________________________

Dr. Bryan McKinnon

Nuclear and Hadron Physics Research
School of Physics and Astronomy
University of Glasgow
Glasgow
G12 8QQ
UK
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