Pi0 Polarizability Meeting Aug 16, 2019
From GlueXWiki
Contents
Meeting Information
Meeting Time And Location
10:00 am ET (JLab time)
CC F224-225
Connecting
Dummy for now: You can connect using BlueJeans Video conferencing (ID: 949 429 419). (Click "Expand" to the right for details -->):
- Make sure you have created a BlueJeans account via your JLab CUE account using this link:
- http://jlab.bluejeans.com (You should only need to do this once)
- Meeting ID: 949 429 419
- (you may need to type this in, depending how you connect)
- If connecting via Web Browser: click this link (no passcode is needed):
- 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
- If connecting via Phone: Dial one of the following numbers and then enter the meeting ID above and hit "#" or "##"
- Dial: (408) 740-7256 (US or Canada only)
- or, List of International Numbers
- If connecting via Polycom unit:
- Dial 199.48.152.152 or bjn.vc
- Enter meeting ID above
Tentative Agenda
- Announcements
- PAC 47
- 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)
- 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.
- PAC47 Report
- TAC Physics Comments
- Other business
- Next meeting
Minutes
Attending: Elton, David, Mark, Rory
- Announcements
- PAC 47
- TAC Physics Comments
- One-pion exchange contribution (C-parity conservation?)
- Rory: this is the chiral anomaly term gpi0->pi0pi0. May not be large but is calculable. Jose can probably do the calculation. It falls into the category of coherent backgrounds (relatively large -t). Interesting in its own right and closely related to the pi0 lifetime.
- Eliminating contributions from iso-scalar resonances (experiment)
- Rory: The gg -> pi0pi0 cross section includes ChiPT calculation + Born terms + resonance terms. These latter diagrams need to be assessed outside of ChiPT. This reaction is a "laboratory for ChiPT."
- We talked about reaching out to other theorists, in particular Dai (from Dai and Pennington) and Barbara Pasquini. Elton will try to contact Dai before the next meeting.
- Sensitivity of cross sections to polarizability (theory)
- This is a task that needs guidance from theory to help us extract polarization physics from the measured cross section.
- Corrections due to photon virtuality (theory)
- Rory: Does inserting the nucleon form factors take care of this?
- Elton: Jose has been concerned with this issue and he can give us an update at the next meeting.
- Mark: According to Jose, Moussallam's calculations are for virtual photons, so we might be able to use his work/framework.
- One-pion exchange contribution (C-parity conservation?)
- 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.
- Mark: There are two steps: 1) from the measured gPb->pi0pi0 cross section determine g g -> pi0 pi0. This is our work as experimentalists. 2) From the g g -> pi0 pi0 cross section extract physics of interest (e.g. polarizability).
- 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.
- 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.
- PAC47 Report
- Rory: At this point, the simulation is in good shape (demonstrated in the LOI is resolution, acceptance, etc). We need theoretical interpretation and address background issues.
- Other business
- Next meeting
- We will plan for our next meeting in two weeks (Aug 30), but it should make sure that Jose, Svetlana and Aleks can participate.