Jet substructure has provided new opportunities for searches and measurements at the LHC, and has seen continuous development since the optimization of the large-radius jet definition used by ATLAS was performed during Run 1. A range of new inputs to jet reconstruction, pile-up mitigation techniques and jet grooming algorithms motivate an optimisation of large-radius jet reconstruction for ATLAS. In this paper, this optimisation procedure is presented, and the performance of a wide range of large-radius jet definitions is compared. The relative performance of these jet definitions is assessed using metrics such as their pileup stability, ability to identify hadronically decaying W bosons and top quarks with large transverse momenta. A new type of jet input object, called a ‘unified flow object’ is introduced which combines calorimeter- and inner-detector-based signals in order to achieve optimal performance across a wide kinematic range. Large-radius jet definitions are identified which significantly improve on the current ATLAS baseline definition, and their modelling is studied using pp collisions recorded by the ATLAS detector at s=13TeV during 2017.
Aad, G., Abbott, B., Abbott, D.C., Abud, A.A., Abeling, K., Abhayasinghe, D.K., et al. (2021). Optimisation of large-radius jet reconstruction for the ATLAS detector in 13 TeV proton–proton collisions. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 81(4) [10.1140/epjc/s10052-021-09054-3].