2008.11.18 Cluster isolation cuts: 2x1 vs. 2x2 vs. 3x3

Ilya Selyuzhenkov November 18, 2008

Data sets:

• pp2006 - STAR 2006 pp longitudinal data (~ 3.164 pb^1)
  after applying gamma-jet isolation cuts (no R_cluster cut applied for this study).
• 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.

2x1, 2x2, and 3x3 clusters definition:

• 3x3 cluster: tower energy sum for 3x3 patch around highest tower
• 2x2 cluster: tower energy sum for 2x2 patch
  which are closest to 3x3 tower patch centroid.
  3x3 tower patch centroid is defined based
  on tower energies weighted wrt tower centers:
  centroid = sum{E_tow * r_tow} / sum{E_tow}.
  Here r_tow=(x_tow, y_tow) denotes tower center.
• 2x1 cluster: tower energy sum for high tower plus second highest tower in 3x3 patch
• r=0.7 energy is calculated based on towers
  within a radius of 0.7 (in delta phi and eta) from high tower

Cuts applied

all gamma-jet candidate selection cuts except 3x3/r=0.7 energy isolation cut

 

Results for 2x1, 2x2, and 3x3 clusters

1. Energy fraction in NxN cluster in r=0.7 radius
   2x1, 2x2, 3x3 patch to jet radius of 0.7 energy ratios
2. Yield vs. NxN cluster energy fraction in r=0.7
   For a given cluster energy fraction yield is defined as an integral on the right
3. Efficiency vs. NxN cluster energy fraction in r=0.7
   For a given cluster energy fraction
   efficiency is defined as the yield (on the right)
   normalized by the total integral (total yield)