2008.04.12 Pythia Gamma-Jets



Pythia Gamma-Jets

Gamma-Jet Yields

During Run 6, the L2-gamma trigger (trigger id 137641) sampled 4717.10 nb-1 of integrated luminosity. By restricting the jet to the Barrel, |ηjet|<1, and the gamma to the Endcap, 1<ηgamma<2, the yield of gamma-jets is estimated as the product of the luminosity, the cross section, and the fraction of events in the phasespace above. The total cross section reported by Pythia for gamma-jet processes at different partonic pT thresholds is listed in the table below. No efficiencies are included.

pT threshold [GeV] Total cross section [mb] Fraction Ngamma-jets
5 6.551E-05 0.0992 30654
6 3.075E-05 0.1161 16840
7 1.567E-05 0.1150 8500
8 8.654E-06 0.1131 4617
9 4.971E-06 0.1223 2868
10 2.953E-06 0.1151 1603

Gamma-Jets pT slope

The pT slope is exp(-0.69*pT)=2^(-pT), so the statistics are halved with each 1 GeV increase in pT.


  1. Yield estimates based on single-particle MC sample, and comparison w/ pythia (Jason Webb)
  2. Pythia estimates of gamma-jet yields (Jim Sowinski)

Pibero Djawotho
Last updated Sat Apr 12 15:15:56 EDT 2008