[Rgd-ana] [EXTERNAL] Re: CAA on vector meson production on nuclear targets

Mon Sep 15 00:06:28 EDT 2025

Dear Pierre, Dear Richard,

Thank you once more for sharing your CAA draft and for the invitation to sign it. I will be pleased to do so and will send you the full list of interested RG-D folks after this Wednesday's meeting, in case they haven't contacted you yet about it.

Those are some minor comments and requests for the coordination of these analyses with the run group:

  1.
In my understanding, based on what has been mentioned about PIDs, the pilot analysis presented in the shared CAA relies only on the EB, except for the BDT-based lepton PID, which is applied to positrons only; is that right? I am unsure if the same method has been considered at any point to improve electron ID and reduce its \pi^- contamination?
  2.
I believe the sampling fraction shown in Fig. 1 is integrated over all sectors, right? I wonder whether similar behavior has been observed in various sectors, or whether it has been verified that this ML technique to refine lepton PID is not sector-dependent. I glanced at Mariana's note (Ref. 38) and didn't see any sector-wise plots. However, the parametrization of the SF_p mean and sigma (Eq.2) is mentioned to be run-dependent and calibrated for each sector. If it's the case, may I know which parametrization you are using for RG-D data, or are you simply using the standard parametrization stored in CCDB (https://clasweb.jlab.org/cgi-bin/ccdb/show_request?request=/calibration/eb/electron_sf:12706:default:2021-02-23_12-13-37 ), as I don't see any entry specific to RG-D run ranges besides this one that goes to infinity. While this SF parametrization is for e-s, what about positrons? (please see next, too)
  3.
In case you are using your own SF parametrization, it would be appreciated if you could share it with the run group members. That brings me to the request to coordinate the common aspects, such as PIDs, vertex cuts, etc., with the RG to optimize the efforts, cross-check results, and also allow the "junior" RG-D analyzers, such as graduate students, to benefit from your experience of analyzing different datasets.
  4.
Please get in touch with Mathieu for the vertex cuts he developed, especially to separate Cu and Sn targets. I understand that these foils are currently not separated due to a lack of statistics, but that will eventually be done. Your feedback on that will also be appreciated.
  5.
For the coordination of efforts, cuts, and/or corrections, we could have some common repository where various routines are stored, but this is something that we could discuss a bit later as all analyses advance.
  6.
In Sub. 3.3.1, it's mentioned that a cut of 4 ns is applied to the vertex time difference between e-s and other particles to ensure they all originate from the same beam bucket, but I believe a 2 ns cut should be used instead, since the beam was simultaneously delivered to 3 halls, not four, during the RG-D run; see this logbook entry<https://logbooks.jlab.org/entry/4189477 >!
  7.
I am a bit curious to know whether you have developed any strategy yet on how to combine RG-D and RG-E datasets, as we ran with different torus and target configurations and vertex positions. That may have an impact on your systematic budget, as cuts for one dataset may not work for the other, etc.

That is all for now. Please keep us updated with your progress. Again, your team's efforts to advance these analysis channels are much appreciated.

  1.

Best,

Lamiaa

**************************************************************************
* Assoc. Prof. Lamiaa El Fassi  /  email: le334 at msstate.edu<mailto:le334 at msstate.edu>
* Chair-Elect, Southeastern Section<https://urldefense.proofpoint.com/v2/url?u=https-3A__engage.aps.org_sesaps_home&d=DwIFAw&c=CJqEzB1piLOyyvZjb8YUQw&r=3uqeDy8nu3dChayXvwFxOAA8GzEdZ-fjsOBs7SphUy4&m=G09Cv6XLO46v8xTKk-oJ4GCNF1gtqLDL_sB2hD_l9fr-1aC18ffrNtVw30MuNW8D&s=PJ_tpFizM4vi47ccBZ_J9IDPmamk6oaKX4qGeKfKEuQ&e= >, American Physical Society<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.aps.org_&d=DwIFAw&c=CJqEzB1piLOyyvZjb8YUQw&r=3uqeDy8nu3dChayXvwFxOAA8GzEdZ-fjsOBs7SphUy4&m=G09Cv6XLO46v8xTKk-oJ4GCNF1gtqLDL_sB2hD_l9fr-1aC18ffrNtVw30MuNW8D&s=N2hotR_V-ZPskROmJ4-o0mc9qp2Yb5rTMSnyo8XB8YU&e= >
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________________________________
From: El Fassi, Lamiaa <le334 at msstate.edu>
Sent: Thursday, September 11, 2025 9:19 PM
To: pierrec at jlab.org <pierrec at jlab.org>; Richard Tyson <tyson at jlab.org>
Cc: rgd-ana at jlab.org <rgd-ana at jlab.org>
Subject: Re: CAA on vector meson production on nuclear targets

Dear Pierre,

Thank you for sharing the CAA and for presenting the progress the team has made so far in exploring new analysis channels, extending the initial RG-D program.

As you mentioned, all run-group members are welcome to read the current draft and share comments. Thank you for offering to sign it.

This serves as an acknowledgment of receiving your write-up, and more details should follow.

Best,

Lamiaa

**************************************************************************
* Assoc. Prof. Lamiaa El Fassi  /  email: le334 at msstate.edu<mailto:le334 at msstate.edu>
* Chair-Elect, Southeastern Section<https://urldefense.proofpoint.com/v2/url?u=https-3A__engage.aps.org_sesaps_home&d=DwIFAw&c=CJqEzB1piLOyyvZjb8YUQw&r=3uqeDy8nu3dChayXvwFxOAA8GzEdZ-fjsOBs7SphUy4&m=G09Cv6XLO46v8xTKk-oJ4GCNF1gtqLDL_sB2hD_l9fr-1aC18ffrNtVw30MuNW8D&s=PJ_tpFizM4vi47ccBZ_J9IDPmamk6oaKX4qGeKfKEuQ&e= >, American Physical Society<https://urldefense.proofpoint.com/v2/url?u=https-3A__www.aps.org_&d=DwIFAw&c=CJqEzB1piLOyyvZjb8YUQw&r=3uqeDy8nu3dChayXvwFxOAA8GzEdZ-fjsOBs7SphUy4&m=G09Cv6XLO46v8xTKk-oJ4GCNF1gtqLDL_sB2hD_l9fr-1aC18ffrNtVw30MuNW8D&s=N2hotR_V-ZPskROmJ4-o0mc9qp2Yb5rTMSnyo8XB8YU&e= >
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* Department of Physics and Astronomy
* 355 Lee Blvd, 125 Hilbun Hall
* P.O.Box 5167
* Mississippi State, MS 39762
***************************************************************************
________________________________
From: pierrec at jlab.org <pierrec at jlab.org>
Sent: Thursday, September 11, 2025 3:31 AM
To: El Fassi, Lamiaa <le334 at msstate.edu>
Cc: rgd-ana at jlab.org <rgd-ana at jlab.org>
Subject: CAA on vector meson production on nuclear targets

Dear Lamiaa, and RG-D enthusiasts,

First of all; thank you for having us present our work yesterday during
the meeting.
We are looking forward to analyse the full RG-D dataset !

Since, the meeting, we have included to the CAA draft some comments we
have received. The current version is attached to this email.
We plan to send the final version of the document on Monday 15th of
September.

If you'd like to sign it, or if you have further comments, please let us
know and we will be glad to change it accordingly by Monday.

Cheers,
Pierre and Richard
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