Pi0 Polarizability Meeting Feb 28, 2020

From GlueXWiki
Jump to: navigation, search

Meeting Information

Meeting Time And Location

10:00 am ET (JLab time)

CC F228

Connecting

You can connect using BlueJeans Video conferencing (ID: 949 429 419). (Click "Expand" to the right for details -->):

  1. Make sure you have created a BlueJeans account via your JLab CUE account using this link:

  2. Meeting ID: 949 429 419
    • (you may need to type this in, depending how you connect)

  3. If connecting via Web Browser: click this link (no passcode is needed):

  4. If connecting via iOS or Android App:
    • Use your JLab e-mail address to log in and then enter the meeting ID given above to join the meeting

  5. If connecting via Phone: Dial one of the following numbers and then enter the meeting ID above and hit "#" or "##"

  6. If connecting via Polycom unit:
    • Dial 199.48.152.152 or bjn.vc
    • Enter meeting ID above


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. Experiment update
  5. Work list for the draft proposal to collaboration
    • Clarification to questions from the PAC where possible
    • Update to theory section (Jose and Mark)
    • Sensitivity of cross section to polarizabilities
      • Jose: The sensitivity is determined by extrapolating into the kinematic region for polarizabilities and will take effort. For now, we will use the estimates from Dai/Pennington.
    • Initial optimization of experiment (e.g. target position)
      • This item will not be attempted for the proposal draft.
    • Analysis of PRIMEX data (Ilya)
    • Assessment of nuclear coherent background (Elton)
      • What is the t-dependence of the sigma (500)?
  6. Other business
  7. Next meeting

Minutes

Attending: Elton, Beni, Ilya, Alexander, Jose, Mark, Rory

  1. Announcements
    • Elton sent an e-mail to Justin to request an extension for our proposal till next Friday. [Note added: Justin replied saying that he felt this schedule would be ok.]
  2. Action Items
  3. Theory update
    • Updates to proposal
    • Jose modified the text and Mark included it into the draft early this week. It includes some clarifications and new references
    • Details of Jose's calculation will be added into an Appendix.
  4. Experiment updates
  5. Coulomb FF (Ilya)
    • Computed the Coulomb FF by modifying the parallel momentum for the increased mass and the cross section scaled for two pions (x2)
    • Rory: How does this differ from the standard electron scattering FF? It is a Glauber calculation that includes absorption corrections for the pion.
    • The calculation shows enhanced secondary maximum relative to single pi0. The higher momentum transfer requires increased precision in the calculation, which has required more computer time.
    • Ilya is now working on obtaining the photon flux for the Primex-eta experiment, so that the data can be properly normalized.
  6. Update (Elton)
    • Elton has used an approximation for the 208Pb FF * sinthe^2 to simulate the nuclear coherent background.
    • The Primakoff peaks at about 0.2 deg (compared to 0.02 deg for single pi0 production). This is due to the increased mass of the final state.
    • The nuclear coherent distribution peaks at about 0.7 deg.
    • The coherent sum of Primakoff and nuclear coherent result in a distribution wider than pure Primakoff but do not exhibit two distinct peaks.
    • Fitting to the distribution can be used to extract the signal, under the assumption that the shapes are known.
    • There was some discussion about examining the distributions coming from lighter nuclei, e.g. 12C.
  7. Work list for the draft proposal to collaboration
    • Clarification to questions from the PAC where possible
    • Update to theory section (Jose and Mark)
    • Sensitivity of cross section to polarizabilities
      • Jose: The sensitivity is determined by extrapolating into the kinematic region for polarizabilities and will take effort. For now, we will use the estimates from Dai/Pennington.
    • Initial optimization of experiment (e.g. target position)
      • This item will not be attempted for the proposal draft.
    • Analysis of PRIMEX data (Ilya)
    • Assessment of nuclear coherent background (Elton, Rory)
      • What is the t-dependence of the sigma (500)?
  8. Schedule for draft
    • Updated sections should be added to the draft by next Wed. That will give us 2 days to polish before submitting our draft to the collaboration.
  9. Other business
  10. Next meeting
    • Next meeting will be next Friday, March 6, 10 am.