Pi0 Polarizability Meeting Dec 18, 2020

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Meeting Information

Meeting Time And Location

11:00 am ET (JLab time)

REMOTE

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Action Items

  1. BGGEN simulations of incoherent backgrounds (Mark) Generated 10 M bggen events
  2. Provide feedback on Gervorkyan calculations (Rory, Elton,...)

Tentative Agenda

  1. Announcements
  2. Action Items
  3. Theory Update
  4. Calculations by Sergey Gevorkyan
  5. Gevorkyan et al PRC 80 (2009) 055201
  6. Experiment Update
    1. Backgrounds
    2. BGGEN simulations of incoherent backgrounds (Mark)
  7. CPP and NPP Readiness Review
  8. Trigger
  9. Other business
  10. Next meeting

Minutes

Attending: Alex, Mark, Elton, Rory, Ilya, Jose

  1. Announcements
  2. Action Items
  3. Theory Update
  4. Calculations by Sergey Gevorkyan
    1. Jose: Would like to see how to incorporate ChiPT into these calculations.
    2. Rory: Went through draft comments in some detail. No effort to make English corrections. Nice summary and report covers our request for him to include the sigma into the calculation for Primakoff and nuclear coherent. Here are a few notes I made; Rory will send detail comments to Ilya
      • Question about whether the large M limit on page 1 is relevant to our situation
      • Would like Sergey to verify that Eq. 8 is generally valid for meson-anti-meson -> gg, even though it was derived for pi+pi-
      • Eq 16 is the primary result for Primakoff production.
      • Elton: How important is the Breit-Wigner approximation for the sigma? Perhaps a more realistic approach should be taken
      • Section 4: Hadronic (nuclear-coherent) production of the sigma. This is important for us
      • First term in Eq. 18 should refer to Eq. 8.
      • Appendix p. 8 refers to Fig. 3, which is not included?
    3. Elton: The paper will be enhanced with some plots with explicit numerical calculations. Elton promised to also send comments on to Ilya to forward to Sergey.
      • The differences in the t slope (B ~ 376 GeV-2) between rho production (with decay to pi+pi-) and sigma nuclear coherent (B ~ 230 GeV-2) is due to the fact that rhos are produced through Pomeron exchange, and sigma nuclear production is via vector meson exchange (rho and omega). Jose: rho is suppressed for isoscalar targets, which was noted by Sergey.
    4. Ilya: Sergey will be happy to receive input and answer questions.
  5. Gevorkyan et al PRC 80 (2009) 055201
  6. Experiment Update
    1. Backgrounds
    2. BGGEN simulations of incoherent backgrounds (Mark)
      • A plot of the angular distribution for bggen events was provided. [Note added: the contribution was updated after the meeting correcting a numerical error]. Based on the estimate, we expect 33 timex more events than generated so far.
  7. CPP and NPP Readiness Review
  8. Trigger
  9. Other business
  10. Next meeting
    • Next meeting: Jan 15, 2001
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