Generalized fragmentation functions for fractal jet observables
Author(s)Elder, Benjamin Tyler; Procura, Massimiliano; Thaler, Jesse; Waalewijn, Wouter Jonathan; Zhou, Kevin
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We introduce a broad class of fractal jet observables that recursively probe the collective properties of hadrons produced in jet fragmentation. To describe these collinear-unsafe observables, we generalize the formalism of fragmentation functions, which are important objects in QCD for calculating cross sections involving identified final-state hadrons. Fragmentation functions are fundamentally nonperturbative, but have a calculable renormalization group evolution. Unlike ordinary fragmentation functions, generalized fragmentation functions exhibit nonlinear evolution, since fractal observables involve correlated subsets of hadrons within a jet. Some special cases of generalized fragmentation functions are reviewed, including jet charge and track functions. We then consider fractal jet observables that are based on hierarchical clustering trees, where the nonlinear evolution equations also exhibit tree-like structure at leading order. We develop a numeric code for performing this evolution and study its phenomenological implications. As an application, we present examples of fractal jet observables that are useful in discriminating quark jets from gluon jets.
DepartmentMassachusetts Institute of Technology. Center for Theoretical Physics; Massachusetts Institute of Technology. Department of Mathematics; Massachusetts Institute of Technology. Department of Physics
Journal of High Energy Physics
Springer Berlin Heidelberg
Elder, Benjamin T., Massimiliano Procura, Jesse Thaler, Wouter J. Waalewijn, and Kevin Zhou. “Generalized Fragmentation Functions for Fractal Jet Observables.” Journal of High Energy Physics 2017, no. 6 (June 2017): 1–54.
Final published version