Difference between revisions of "Pi0 Polarizability Meeting Dec 20, 2019"

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(Minutes)
Line 71: Line 71:
 
#* Recall: There are two Compton Tensors A and B (C does not contribute)
 
#* Recall: There are two Compton Tensors A and B (C does not contribute)
 
#* Use the model by Holstein and Donahue to calculate f0 and f2 form factors that determine A and B
 
#* Use the model by Holstein and Donahue to calculate f0 and f2 form factors that determine A and B
#* f0 and f2 are determined by the s-wave phase shifts. Uses parameterization of Gasser, Leutweiler and Colangelo.
+
#* f0 and f2 are determined by the s-wave phase shifts through various integrals. Uses parameterization of Gasser, Leutweiler and Colangelo.
#* The phase shifts are well known to about  
+
#* The phase shifts are well known to about mpipi~1.8 GeV. The integrals go to infinity, but the systematic dependence on the cutoff is relatively small at small mpipi.\
 +
#* The task of using this work to compute the cross section is close and Jose expects to have something we can use in early Jan.
 +
#* Jose will also share this work with our other theory colleagues for checking and feedback.
 
# Experiment update
 
# Experiment update
 +
#* Elton: His program to generate events with background (according to assumptions that went into the LOI) has been revived using Geant4 in the CPP case. This will allow us to implement the full geometry (including muon chambers) into the simulation. Technical obstacles have been overcome and 100,000 events have been passed through from generation through amplitude fits.
 +
#* This system will now be checked with pi0pi0 case and verify it is also operational with Geant4.
 +
# Work for the proposal
 +
#* Need to use Jose's work for simulation of signal (Primakoff) process. This can be used to study accuracy of extraction of signal and optimization of experiment (e.g. target position).
 +
#* Need to get a good description of the nuclear coherent background processes (e.g. working with Sergey) to add to the simulation.
 
# Other business
 
# Other business
 
# Next meeting
 
# Next meeting
 +
#* Our next meeting with be Jan 17. Happy Holidays!

Revision as of 15:30, 20 December 2019

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)
  2. Formulate questions for Serguei (Elton and Ilya) Ask Sergey to calculate nuclear coherent sigma production on lead.
  3. Specify s-wave parameterization (Elton and Lingyun) Elton passed references to a limited parameterization; Lingyun has been copied on e-mails.

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Theory update
  4. Experiment update
  5. Other business
  6. Next meeting

Minutes

Attending: Elton, Jose, Rory, Mark

  1. Announcements
    • Accelerator is shutting down this evening. No beam since yesterday swing. The accelerator will be manned over the holiday and they expect a quick start in Jan.
  2. Action Items
    • Questions to Sergey
    • We decided that the main request to Sergey is to ask if he can calculate the coherent sigma production on lead. This includes final state interactions (FSI) of the two pions.
    • Rory: This calculation should be doable for Sergey given he machinery he has developed for pi0 Primakoff.
    • Elton: In particular the t dependence of this reaction would be useful.
    • Jose: The calculation should be similar for the charged pion production also. Both involve strong production of two pions although FSI may be different.
  3. Theory update
    • Jose's Notes Dec 19 2019
    • Recall: There are two Compton Tensors A and B (C does not contribute)
    • Use the model by Holstein and Donahue to calculate f0 and f2 form factors that determine A and B
    • f0 and f2 are determined by the s-wave phase shifts through various integrals. Uses parameterization of Gasser, Leutweiler and Colangelo.
    • The phase shifts are well known to about mpipi~1.8 GeV. The integrals go to infinity, but the systematic dependence on the cutoff is relatively small at small mpipi.\
    • The task of using this work to compute the cross section is close and Jose expects to have something we can use in early Jan.
    • Jose will also share this work with our other theory colleagues for checking and feedback.
  4. Experiment update
    • Elton: His program to generate events with background (according to assumptions that went into the LOI) has been revived using Geant4 in the CPP case. This will allow us to implement the full geometry (including muon chambers) into the simulation. Technical obstacles have been overcome and 100,000 events have been passed through from generation through amplitude fits.
    • This system will now be checked with pi0pi0 case and verify it is also operational with Geant4.
  5. Work for the proposal
    • Need to use Jose's work for simulation of signal (Primakoff) process. This can be used to study accuracy of extraction of signal and optimization of experiment (e.g. target position).
    • Need to get a good description of the nuclear coherent background processes (e.g. working with Sergey) to add to the simulation.
  6. Other business
  7. Next meeting
    • Our next meeting with be Jan 17. Happy Holidays!