Development and Performance of the Combined Jet Mass - LHCC Poster

The jet mass is a crucial discriminating variable in studies involving jet substructure.The calorimeter mass has been the canonical mass definition during the first run of ATLAS. This poster describes how the calorimeter mass can be combined with the track-assisted jet mass (which is obtained by associating inner detector tracks with calorimeter jets), to yield a new jet mass definition, the combined jet mass. The combined jet mass is constructed in such a way as to in principle, achieve a superior mass resolution over a much wider kinematic range. The process of constructing the combined mass from the calorimeter and track-assisted mass resolutions is presented, followed by a review of the performance of the combined jet mass in mass reconstruction. The combined jet mass is shown to offer significant improvements over the calorimeter and track-assisted mass approaches, and as a result it forms the new jet mass recommendation for ATLAS analyses targeting Moriond, 2017.