PERFORMANCE OF A MULTIVARIABLE CALIBRATION FOR ELECTRONS AND PHOTONS WITH THE ATLAS HIGH-LEVEL TRIGGER

Abstract

A multivariate calibration technique is implemented for online electron and photon candidatesto account for energy loss upstream of the electromagnetic calorimeter and for lateraland longitudinal shower leakage in the ATLAS experiment. The online calibration is necessaryto improve the energy resolution of the electrons and photons with respect to the offlineobjects to ensure a sharp turn-on response of the trigger system. In this case, boosted decisiontrees have been applied to calibrate the response of the calorimeters in the detector forelectrons and photons, and the performance of the calibration has been measured throughdetermination of the resolution of the electron and photon energy for both online and offline.