The attached plots compare the official pythia production with the data.

Description of Attached Files

One pdf file is provided for each of the following variables:

• Mass of two gamma system
• Energy of two gamma system
• Energy asymmetry between two gammas (Z_gammagamma)
• vertex Z distribution
• Two gamma system physical eta

Each page of the pdf represents one pT bin.

Cuts

All cuts are identical for data and Monte Carlo and for all attached pdfs, with two exceptions: the plot of the physical eta distribution does not include the physical eta cut, and likewise the vertex Z cut is not applied for the vertex Z distribution. The cuts are:

• Z vertex cut:
  • If TPC vertex available, then cut is +/- 120 cm
  • If not, then BBC time bin must be in [6,10]. [note: EEmcTrees remade using the blue values from this blog].
• Trigger cut eemc-mb-http-L2gamma, using runs from just the last threshold values (trig-C from this blog)
• Cuts applied to pi0 candidate (two-gamma system)
  • M < 0.6 GeV
  • phys eta in [0.8, 2.0]
• Cuts applied to each photon
  • E > 2.0 GeV (TSIU SMD clustering algorithm), E > 1.5 GeV (IU SMD clustering algo)
  • preshower 1 E < 40 MeV
  • detector eta in [1.11,1.96] (see this blog)
  • SMD E / Tow E > 0.006

Conclusions

Mass

The descrepancies in the invariant mass distributions have been discussed previously, and a study regarding them can be found in Section 5e of the most recent draft of Part I of the Analysis Note.  Note, this is a very early draft and the presentation and author list are still being updated and finalized. 

Energy

The Monte Carlo seems to have a wider energy distribution per pT for most pT bins, especially the lower pT bins.  This is most likely a result of the descripancies seen in the vertex distribution.

Energy Asymetry

The agreement is quite good.

Vertex Z distribution

The comparision is quite poor in the lower pT region.  Note: the trigger emulator is applied to the Pythia sample, and the same threshold are used.  Also note the cut at Z +/- 120 in the Monte Carlo, which was enforced when the production was generated.

Physical Eta Distribution

Is fairly good in the lower pT bins, and quite good in the higher pT bins.