Abstract
The reconstruction of the signal from hadrons and jets emerging from the proton–proton collisions
at the Large Hadron Collider (LHC) and entering the ATLAS calorimeters is based
on a three-dimensional topological clustering of individual calorimeter cell signals. The
cluster formation follows cell signal-significance patterns generated by electromagnetic and
hadronic showers. In this, the clustering algorithm implicitly performs a topological noise
suppression by removing cells with insignificant signals which are not in close proximity to
cells with significant signals. The resulting topological cell clusters have shape and location
information, which is exploited to apply a local energy calibration and corrections depending
on the nature of the cluster. Topological cell clustering is established as a well-performing
calorimeter signal definition for jet and missing transverse momentum reconstruction in ATLAS.