2008.10.15 Comparison of gamma-jets from Michael's filtered events vs. old MC samples

Ilya Selyuzhenkov October 15, 2008

Data sets:

• pp2006 - STAR 2006 pp longitudinal data (~ 3.164 pb^1)
  after applying gamma-jet isolation cuts (note: R_cluster > 0.9 is used below).
• gamma-jet[gamma-filtered] - data-driven Prompt Photon [p6410EemcGammaFilter] events.
  Partonic pt range 2-25 GeV.
• QCD jets[gamma-filtered] - data-driven QCD [p6410EemcGammaFilter] events.
  Partonic pt range 2-25 GeV.
• gamma-jet [old] - data-driven Pythia gamma-jet sample (~170K events).
  Partonic pt range 5-35 GeV.
  Details on jet trees production for Michael's gamma filtered events can be found here.
• QCD jets [old] - data-driven Pythia QCD jets sample (~4M events).
  Partonic pt range 3-65 GeV.

Some observations:

• Both Fig. 1a vs. Fig. 1b shows good statistics for old and new (gamma-filtered) MC gamma-jet samples
• Fig. 1c shows poor statistics for QCD background sample
  within partonic pt range 5-10GeV (only 3 counts for "pre1=0 & pre2=0" condition).
  Fig. 1d (new QCD sample) has much more counts in the same region,
  but it is still only 20-25 entries for the case when
  none of EEMC pre-shower layers fired (upper left corner - our purest gamma-jet sample).
  This may be still insufficient for a various cuts systematic study.
• Fig. 2 and Fig. 3 shows nice agreement between data and MC
  for both old and new (gamma-filtered) MC samples.
  For pre-shower1>0 case this agreement persists across full range of gamma's pt (7GeV and above).
  Upper plots in Fig. 3 shows some difference between data and Monte-Carlo,
  what could be effect from l2gamma trigger,
  which has not been yet applied for MC events.

Figure 1a: partonic pt for gamma-jet [old] events
after analysis cuts and partonic pt bin weighting
(Note:Arbitrary absolute scale)

Figure 1b: partonic pt for gamma-jet [gamma-filtered] events after analysis cuts.
Michael's StBetaWeightCalculator has been used to caclulate partonic pt weights

Figure 1c: partonic pt for QCD jets [old] events
after analysis cuts and partonic pt bin weighting
(Note:Arbitrary absolute scale)

Figure 1d: partonic pt for QCD jets [gamma-filtered] events after analysis cuts.
Michael's StBetaWeightCalculator has been used to caclulate partonic pt weights

Figure 2: reconstructed gamma pt: old MC vs. pp2006 data (scaled to the same luminosity)

Figure 3: reconstructed gamma pt: gamma-filtered MC vs. pp2006 data (scaled to the same luminosity)