Studies of Hadronic Trigger Background Composition at ATLAS

The ATLAS detector at the LHC uses a custom two-level trigger system to save 1 kHz of events from a 40 MHz bunch-crossing rate. It is of interest to be able to predict trigger rates using Monte Carlo simulations. The transverse momentum of jets and missing transverse energy of Pythia simulations with different hard-scatter truth jet pT ranges were normalized to data selected using the jet trigger. This gives effective correction factors and is an appealing method for deriving rate estimates. This method is presented as a better process for simulating rates than the current method, which only uses minimum bias Monte Carlo simulation.