Lee Pondrom University of Wisconsin Pythia status 8 Feb 2010 Lee Pondrom University of Wisconsin
2->2 Pythia compared to nlojet++ born and jet_chi program
Normalization Each set of four mass plots has one overall normalization. All programs agree on the mass dependence of the cross section. Nlojet++ born agrees better with Pythia as the mass increases.
The earlier plot
Discrepancy at low Fixed by symmetrizing the cross sections for non-identical partons in the final state because the jets are indistinguishable. The cross sections are symmetrized ut. Explained in Barger and Phillips p 305.
conclusion We understand Pythia. It agrees well with the data, and strengthens the Pythia based quark substructure analysis. Further analysis using nlojet++, which is not understood, is problematic.