[Clas12_verystrange] slides and meeting

[Lei Guo]

Hi, All,

Attached are four slides I picked from Igor's presentation, and made  
some small modifications.
I've also received comments from one PAC reader Ulrike Thoma:

* You are discussing ~4000 reconstructed Omega^- and several
  million of Cascade states which will become observable

  - with 4000 reconstructed Omega^- events, do you really
    expect to see something like excited states ?
    I would assume that in this case an determination of
    the quantum numbers would not be possible, correct ?

    Do I then understand correctly that the main issue in
    the Omega^- sector is to understand the production mechanism
    of the groud state Omega^- ?


* You are discussing that the observation of the Omega^- in
  gamma p environment is of specific interest.
  It did not become entirely clear to me why ? Do you relate this
  to the strangeness content in the proton ?
  Or what can I learn about physics or other processes if I
  have understood the production mechanism of the omega^-
  in photoproduction ?
  (Sorry if I have missed something in the proposal)


* What is the mass resolution you expect to get for the
  Cascade^0 and Cascade^- ground states ?
  Which systematic error do you expect ?


* One page 13 you are discussing the reaction gamma p -> K^+ K^0 X
  and you are mentioning the since the strangeness of the K^0 is
  not defined background from pions misidentified as kaons might
  be significant : I would assume that a cut on the detached
  K^0->pi+pi- vertex should solve this problem ?


* I got confused with your coordinate systems. Do you have a
  figure which defines your coordinate system and the naming
  you are using for the different planes ?
  (e.g. related to Fig.7)


* Fig.12(right) : why is the band-like vertical structure
  not running through the complete phase space area ?
  Is this an area of reduced acceptance ?
  Is yes, why do I see events in the same area in the left figure ?


* Forward tagger: how are the crystals read out in this high rate
  environment ?  Are they operated at room temperature ?

  Which energy dependent resolution is expected to be reached
  with the forward tagger ?



* Fig.21 shows all particles of the events at the same time but
  what is the probability that one of the particles in an event
  has a momentum above 2 GeV (and is therefore misidentified)?


* How realistic is the FASTMC in respect to momentum resolution ?
  Are in the FASTMC the tracks really reconstructed or is just
  some smearing of the momentum done ?

  You are not considering an uncertainly in l, why ?


* What kind of reactions are included in the 100k Pythia background
  events ?  (sorry for not knowing this but I never used Pythia so far)


* Are the simulations done using the half or full magnetic field ?
  I understood that at least parts of them are done at half field,
  while the measurement will take place at full field ...


* I am missing a study which tells me how well the quantum numbers
  of the resonances can be determined from the obtained data.

  How many good events are needed above background to allow
  for a quantum number determination ?

  Which part of the multidimensional phase space is covered ?
  Are there e.g. areas in cos(theta) of the hyperons where the
  recoil polarization cannot be determined.

  It is very difficult to judge based on the proposals what the
  restrictions of the PWA might later be due to uncovered regions
  in phase space.


* The baryon resonances can also be studied using GlueX. What are
  the advantages doing this with CLAS12 relative to GlueX ?
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      /   ___  ___  Lei Guo _______________________
     L_O_/ ____ Florida International University____/_/
         \   |             Physics Dept., CP  
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      /    \ |             Miami, FL  
33199        /                       /  /
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