Pi0 Polarizability Meeting Jan 31, 2020

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Meeting Information

Meeting Time And Location

10:00 am ET (JLab time)

CC F228


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Action Items

  1. ChiPT calculation to one loop with Coulomb photon (Svetlana and Aleks)

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Theory update
  4. Review of recent paper on gamma*gamma*->pipi
  5. Experiment update
  6. Other business
  7. Next meeting



  • Grenfell: Svetlana Barkanova
  • JLab: Alexander Austregesilo, Jose Goity, Mark Ito (chair), David Lawrence, Beni Zihlmann
  • UMass: Rory Miskimen


  • Elton Smith was busy giving a Hall D Safety Walkthrough at the time of the meeting and sent his regrets.
  • Collaboration Meeting. The Collaboration meeting is coming up in two weeks. We are already on the agenda for Friday at 16:25. We thought that Elton would be a good candidate to give the talk.
  • PAC48 Call For Proposals. The submission deadline is Monday, June 1, 2020. The PAC will be held the week of July 13, 2020. GlueX Collaboration Bylaws require a draft 90 days in advance of a collaboration vote. If that vote is to occur before submission to the PAC, a draft needs to be submitted to the collaboration before the end of February. It is thought that this need not be the final version, that it is indeed a draft.

Theory Update

  • Svetlana reported that work continues with the χPT calculation to one loop with a Coulomb photon that she is working on with Aleksandrs Aleksejevs.
  • Jose reported that he is very close to completing his calculation of the cross section. There remains only one tricky parametrization for the dispersive contribution.

Review of recent paper on γ*γ*→ππ

Rory reviewed the recent paper from Danilkin, Deineka, and Vanderhaeghen. He summarized the main points from the paper and gave some useful references for further reading. See his slides for the details.

Barbara Pasquini originally referred Rory to this paper. She sees is as an extension of her earlier paper (in Rory's references) that noted compatibility between the approaches of chiral perturbation theory and dispersive theory. Svetlana is working with Igor D. and Marc V. on other topics. She will contact Marc for comment on the relation of this paper to neutral pion polarizability.

Next Meeting

We thought we should meet again in a week, Friday, February 7 at 10 am EST, since the collaboration meeting will be in two weeks time.