2008/02/29 by Matteo Cacciari, Gavin P. Salam, Gavin P Salam +1 · 3 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #High-Energy Particle Collisions Research #Particle physics theoretical and experimental studies #hep-ph
paper · pdf · doi:10.1088/1126-6708/2008/04/005
published as JHEP0804:005,2008 · 42 pages, 17 figures. Improved text. Added a summary table of all definitions in Conclusions. Version published in JHEP
openalex publication_date 2008/04/01 · arxiv created 2008/04/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
The area of a jet is a measure of its susceptibility to radiation, like pileup or underlying event (UE), that on average, in the jet's neighbourhood, is uniform in rapidity and azimuth. In this article we establish a theoretical grounding for the discussion of jet areas, introducing two main definitions, passive and active areas, which respectively characterise the sensitivity to pointlike or diffuse pileup and UE radiation. We investigate the properties of jet areas for three standard jet algorithms, kt, Cambridge/Aachen and SISCone. Passive areas for single-particle jets are equal to the naive geometrical expectation πR2, but acquire an anomalous dimension at higher orders in the coupling, calculated here at leading order. The more physically relevant active areas differ from πR2 even for single-particle jets, substantially so in the case of the cone algorithms like SISCone with a Tevatron Run-II split--merge procedure. We compare our results with direct measures of areas in parton-shower Monte Carlo simulations and find good agreement with the main features of the analytical predictions. We furthermore justify the use of jet areas to subtract the contamination from pileup.