Pi0 Polarizability Meeting Aug 30, 2019

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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. Contact Dai regarding the pi0pi0 proposal (Elton).

Tentative Agenda

  1. Announcements
    • Wiki pages moved to open repository
  2. Action Items
    1. Lingyun Dai, Hunan University: Changsha, Hunan, CN (dailingyun@hnu.edu.cn)
  3. PAC 47
    1. TAC Physics Comments
      • One-pion exchange contribution (C-parity conservation?)
      • Eliminating contributions from iso-scalar resonances (experiment)
      • Sensitivity of cross sections to polarizability (theory)
      • Corrections due to photon virtuality (theory)
    2. email from Elton and Mark to PAC Reviewer Steve Dytman. Homework to prepare for a proposal (Questions not answered by the LOI):
      • So far we have only qualitatively investigated backgrounds, but do not find any particular reactions that have not been considered for pi0 and pi+pi- Primakoff reactions. Detailed studies needed.
      • Determine how backgrounds will affect the determination of the pi0pi0 Primakoff cross section.
      • Evaluate sensitivity to run time. Need to justify requested beam time.
      • Develop the case for measuring pi0pi0 production at threshold aside from the determination of the polarizability.
    3. PAC47 Report
  4. Other business
  5. Next meeting

Minutes

Attending: David, Elton, Jose, Ilya, Beni, Mark (JLab); Rory (UConn); Svetlana, Aleks (MU)

  1. Announcements
    • Wiki pages moved to open repository
  2. Action Items
    1. Lingyun Dai, Hunan University: Changsha, Hunan, CN (dailingyun@hnu.edu.cn)
  3. PAC 47
  4. TAC Physics Comments
    1. One-pion exchange contribution (C-parity conservation?)
      • Jose: there is a chiral g -> pi+pi-pi0, but not g -> pi0 pi0 pi0.
    2. Eliminating contributions from iso-scalar resonances (experiment)
    3. Sensitivity of cross sections to polarizability (theory)
    4. Corrections due to photon virtuality (theory)
      • Jose: There are two issues 1) virtuality of exchanged photon 2) re-scattering effects in the target.
  5. email from Elton and Mark to PAC Reviewer Steve Dytman. Homework to prepare for a proposal (Questions not answered by the LOI):
    1. So far we have only qualitatively investigated backgrounds, but do not find any particular reactions that have not been considered for pi0 and pi+pi- Primakoff reactions. Detailed studies needed.
      • Ilya: Primakoff eta data taken this spring might be useful to check backgrounds. Calibration is at the 1% level. No pi0 seen in the CompCal.
    2. Determine how backgrounds will affect the determination of the pi0pi0 Primakoff cross section.
    3. Evaluate sensitivity to run time. Need to justify requested beam time.
      • Ilya: We should consider both running time and which targets to use. Different targets will have different sensitivities to background. Having multiple targets will allow studies of systematics. Primakoff-eta was originally proposed on H and He, but now consideration is given to using Carbon instead of H. But possible contamination of data with transitions to excited states of Carbon were a concern.
      • Beni: Need to minimize the amount of vacuum near the target to eliminate sources that don't come from the target since we do not measure the vertex.
      • Mark: Note that once the experiment is decoupled from CPP, one may wish to optimize not only targets, but also beam energy or other parameters.
      • Ilya: It is useful to have as much commonality with CPP as possible for reasons of comparison. For example pi+pi- rescattering to pi0pi0 makes these reactions interconnected.
    4. Develop the case for measuring pi0pi0 production at threshold aside from the determination of the polarizability.
      • Elton: It would be useful to develop a physics case for a precision measurement at threshold in addition to its sensitivity to polarizability.
  6. PAC47 Report
  7. Other business
  8. Next meeting
    • We will continue meeting at 10 am on Friday and we will meet bi-weekly. Next meeting is Sep 13.
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