05/06/2020

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Present: M.D., A.D., S.Š, J.S.

General: Following the GlueX review report, it was announced at the GlueX bi-weekly meeting that the GlueX board has formally endorsed the proposal to be reviewed by the collaboration.

  • Our own list of points to clarify re. the proposal, based on meeting with Garth and Frank:
    • Change (M. Dalton):
      • "Primary goal" to "Early goal" (meaning what we can learn with an easy analysis)
      • "Secondary goal" to "longer term goal" (meaning it involves a more complicated analysis)
    • Clarify that the proton GDH running integral has overshot the sum rule predictions and while the missing part is expected to be negative from Regge, the evidence for that from ELSA data is anecdotal. (M. Dalton)
    • Add the running integral plot to the proposal (make the running integral for the neutron), with the LEGS data included. Specify that this is all the data available so far. (M. Dalton)
    • Clarify that our simulated prediction of the proposed measurement were obtained using the best Regge estimate available. It was unclear to Garth and Frank what was in the simulated data. (M. Dalton)
    • Instead, or in addition, to Fig. 1, use the PDG figure that show the pomeron-related increase of the unpolarized cross-section. (M. Dalton)
    • The illustration based on Fig. 1 on what we would have missed (the divergence of the unpolarized integral) if unpolarized data stopped at 2.9 GeV seems to not have been clear to Garth and Frank. (M. Dalton)
    • Clarify and extend the discussion on the 25% improvement of accuracy for the verification on the proton GDH sum rule. (A. Deur)
    • Illustration of what we could learn about quark substructure:
      • Make it more prominent in the introduction.
      • Mention it in the conclusion
      • Instead (or in addition) of assuming that we will find that the sum rule is valid, and computing the compositeness limit within this assumption, discuss what we would learn on quark compositeness if the sum rule is violated by, say, 3σ. (A. Deur)
    • Remove in details on HDice. (Just say we are using FROST, unless a bigger program warrant the use of HDice) (A. Deur)
    • Clarify that the 3 PS settings are different from the (unique) tagger setting. (M. Dalton)
    • Clarify the XEFT part (Garth thought we were directly measuring the Forward Compton reaction). (Simon Širca)


  • M.D.:
    • Rewriting the proposal.
    • BH event generator:
  • J.S.:
    • Will discuss with Simon and then the GlueX board Simon's commitment to the GlueX collaboration, would the proposal be accepted by the PAC. The by-law is "All proponents of such proposed experiments must be members of the GlueX Collaboration, or have a plan approved by the EG and CB for joining the Collaboration and participating in ongoing GlueX experiments."
  • S.Š:
    • Sent more data sets for p and n from MAMI and ELSA.
    • Produced [BH figure].


  • A.D.: