Measuring the ATLAS calorimeters’ response using W→τ+ν→π+ν+ν interaction

One of the main issues in the ATLAS calorimeters is the insufficient amount of statistics available to measure the calorimeter’s response at high track momenta. We analyzed a new way to measure this while achieving a better uncertainty than the one obtained with low pile-up minimum bias collisions (traditional method), looking into π production from W→τ+ν events. Looking into simulated single-particle events, we used Eventshape_rhoKt4EM (which we shall name ρ) to correct for pile-up effects and showed that it works effectively at high energies. We proceeded to work with 280 < max(WpT) < 500 GeV, and no bottom/charm-jets W→τ+ν simulations. Using cuts on the EMB detectors, the probability of the cluster to have detected an EM particle, dR and track to vertex match, we were able to single out the single π events from the τ decay. Adding extra decays of the W boson into electrons and muons, we were still able to isolate the desired event. Applying these cuts also worked when using 2017 data produced at the LHC, showing that this method would work on measuring E/p at high momenta.