Difference between revisions of "Pi0 Polarizability Meeting Sep 13, 2019"

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# Announcements
 
# Announcements
 
# Action Items
 
# Action Items
# PAC 47
+
# [[Media:PionPolarizabilities-Theory.pdf | Theory Priorities (DRAFT)]] (Jose)
#* [[Media:PionPolarizabilities-Theory.pdf | Theory Priorities]] (Jose)
+
 
# Other business
 
# Other business
 
# Next meeting
 
# Next meeting
Line 59: Line 58:
 
# Announcements
 
# Announcements
 
# Action Items
 
# Action Items
## Lingyun Dai, Hunan University: Changsha, Hunan, CN (dailingyun@hnu.edu.cn)
+
## Elton has not received any response from emails to Dai. Lingyun Dai, Hunan University: Changsha, Hunan, CN (dailingyun@hnu.edu.cn)
# PAC 47
+
# [[Media:PionPolarizabilities-Theory.pdf | Theory Priorities]] (Jose)
#* [[Media:PionPolarizabilities-Theory.pdf | Theory Priorities]] (Jose)
+
## Corrections due to virtuality. Jose mentioned that his recollection was that estimates of higher order corrections was 30%. There are both higher order ChiPT corrections in addition to corrections due to virtuality of the exchanged photon
 +
##* Aleks suggested that one could calculate Compton scattering off a pi0 at one loop and evaluate the corrections due to virtuality in that case. It was agreed that this would be a good start
 +
## Dispersive approach
 +
##* Evaluating the impact of high mass data on the  experiment may be important for the proposal.
 +
##* Elton will provide a t distribution for the reaction.
 +
##* Current group of theorists do not have great expertise in this area. One would need to learn about the approach and contact experts in this field.
 +
##* We will reach out to experts in these areas (Pasquini, Moussallam, Dai and others) to see if they would be willing to support this effort.
 +
## Move from gg*->pi0pi0 to gA->pi0pi0A.
 +
##* Jose is almost finished with this calculation.
 +
## Sensitivity of polarization to cross section
 +
##* This depends on which meson exchanges (e.g. rho?) contribute to the reaction. One needs to identify the main exchanges.
 +
##* Evaluate existing literature and create context for application to this proposal.
 +
## Get control over all other contributions to the cross section, including nuclear corrections.
 +
##* Take advantage of PRIMEX experience (single pi0) to see if one can extrapolate to this proposal (2 pi0s).
 +
##* Engage Serguei to do some of the calculations for this case.
 +
# Calculations of gp->pi0pi0 p (Aleks)
 +
#* Aleks showed the diagrams contributing to gp -> pi0 pi0 p using ChiPT as a first step toward understanding the Primakoff reaction.
 +
#* Elton: We might want to consider a large Z isoscaler source of virtual photons, which might be closer to the experimental situation.
 +
#* Mark: Absolute cross section for reaction not as important as angular distribution for use in separating out nuclear coherent from the Primakoff signal.
 +
#* Jose: Need to assess importance of various diagrams (see #4 above) in order to prioritize calculations.
 
# Other business
 
# Other business
 
# Next meeting
 
# Next meeting
 +
#* Sep 27 at 10 am.

Revision as of 13:22, 13 September 2019

Meeting Information

Meeting Time And Location

10:00 am ET (JLab time)

CC F228

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Action Items

  1. Theory priority list and how to address them (Jose) Jose presented a list which was discussed by the group.

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Theory Priorities (DRAFT) (Jose)
  4. Other business
  5. Next meeting

Minutes

Attending: Alex (CMU); Mark, Jose, Beni, Elton (JLab); Aleks, Svetlana (MUN) ; Ilya, Rory (UMass).

  1. Announcements
  2. Action Items
    1. Elton has not received any response from emails to Dai. Lingyun Dai, Hunan University: Changsha, Hunan, CN (dailingyun@hnu.edu.cn)
  3. Theory Priorities (Jose)
    1. Corrections due to virtuality. Jose mentioned that his recollection was that estimates of higher order corrections was 30%. There are both higher order ChiPT corrections in addition to corrections due to virtuality of the exchanged photon
      • Aleks suggested that one could calculate Compton scattering off a pi0 at one loop and evaluate the corrections due to virtuality in that case. It was agreed that this would be a good start
    2. Dispersive approach
      • Evaluating the impact of high mass data on the experiment may be important for the proposal.
      • Elton will provide a t distribution for the reaction.
      • Current group of theorists do not have great expertise in this area. One would need to learn about the approach and contact experts in this field.
      • We will reach out to experts in these areas (Pasquini, Moussallam, Dai and others) to see if they would be willing to support this effort.
    3. Move from gg*->pi0pi0 to gA->pi0pi0A.
      • Jose is almost finished with this calculation.
    4. Sensitivity of polarization to cross section
      • This depends on which meson exchanges (e.g. rho?) contribute to the reaction. One needs to identify the main exchanges.
      • Evaluate existing literature and create context for application to this proposal.
    5. Get control over all other contributions to the cross section, including nuclear corrections.
      • Take advantage of PRIMEX experience (single pi0) to see if one can extrapolate to this proposal (2 pi0s).
      • Engage Serguei to do some of the calculations for this case.
  4. Calculations of gp->pi0pi0 p (Aleks)
    • Aleks showed the diagrams contributing to gp -> pi0 pi0 p using ChiPT as a first step toward understanding the Primakoff reaction.
    • Elton: We might want to consider a large Z isoscaler source of virtual photons, which might be closer to the experimental situation.
    • Mark: Absolute cross section for reaction not as important as angular distribution for use in separating out nuclear coherent from the Primakoff signal.
    • Jose: Need to assess importance of various diagrams (see #4 above) in order to prioritize calculations.
  5. Other business
  6. Next meeting
    • Sep 27 at 10 am.