Abstract
We introduce collinear drop jet substructure observables, which are unaffected by contributions from collinear radiation, and systematically probe soft radiation within jets. These observables can be designed to be either sensitive or insensitive to process-dependent soft radiation originating from outside the jet. Such collinear drop observables can be exploited as variables to distinguish quark, gluon, and color neutral initiated jets, for testing predictions for perturbative soft radiation in Monte Carlo simulations, for assessing models and universality for hadronization corrections, for examining the efficiency of pileup subtraction methods, and for any other application that leaves an imprint on soft radiation. We discuss examples of collinear drop observables that are based both on clustering and on jet shapes. Using the soft-collinear effective theory we derive factorization expressions for collinear drop observables from QCD jets, and carry out a resummation of logarithmically enhanced contributions at next-to-leading-logarithmic order. We also identify an infinite class of collinear drop observables for which the leading double logarithms are absent.
Highlights
Jets are collimated sprays of particles observed in high energy colliders
We introduce collinear drop jet substructure observables, which are unaffected by contributions from collinear radiation, and systematically probe soft radiation within jets
These observables can be designed to be either sensitive or insensitive to processdependent soft radiation originating from outside the jet. Such collinear drop observables can be exploited as variables to distinguish quark, gluon, and color neutral initiated jets, for testing predictions for perturbative soft radiation in Monte Carlo simulations, for assessing models and universality for hadronization corrections, for examining the efficiency of pileup subtraction methods, and for any other application that leaves an imprint on soft radiation
Summary
Jets are collimated sprays of particles observed in high energy colliders. They emerge from energetic quarks and gluons produced in a hard collision, which are converted into final state particles through parton splitting and hadronization. An important ingredient for testing such improvements is to define new types of observables that are sensitive to different regions of phase space, or which test aspects of the shower beyond the leading collinear approximation Another driving force for making progress in understanding hard collisions has been systematically improvable field theoretic methods for making predictions for jet data. This is accomplished by using jet grooming procedures [45–49] to suppress soft contributions to jet observables by systematically removing soft and wide-angle particles within the jet This leads to groomed observables that are much less sensitive to the dynamics of any processes occurring outside of the jet, such as initial and final state soft radiation from other jets, underlying event, and pileup. The goal here is to consider jet observables that are sensitive to physics in various soft phase space regions This makes collinear drop observables ideal for studying perturbative soft dynamics, hadronization, underlying event, and pileup in proton-proton collisions.
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