Abstract
We propose a modified definition of the jet charge, the "dynamic jet charge", where the constant jet momentum fraction weighting parameter, $\kappa$, in the standard jet charge definition is generalized to be a function of a dynamical property of the jet or the individual jet constituents. The dynamic jet charge can complement analyses based on the standard definition and give improved discrimination between quark and gluon initiated jets and between jets initiated by different quark flavors. We focus on the specific scenario where each hadron in the jet contributes to the dynamic jet charge with a $\kappa$-value dynamically determined by its jet momentum fraction. The corresponding dynamic jet charge distributions have qualitatively distinct features and are typically characterized by a multiple peak structure. For proton-proton collisions, compared to the standard jet charge, the dynamic jet charge gives significantly improved discrimination between quark and gluon initiated jets and comparable discrimination between $u$- and $d$-quark initiated jets. In Pythia simulations of heavy ion collisions, the dynamic jet charge is found to have higher jet discrimination power compared to the standard jet charge, remaining robust against the increased contamination from underlying event. We also present phenomenological applications of the dynamic jet charge to probe nuclear flavor structure.
Highlights
Identifying the electric charge of partons that emerge from the hard scattering process to initiate the formation of jets can be useful in the search for new physics and testing various aspects of the Standard Model
In the context of these various tools developed for jet discrimination, we introduce a modified definition of the standard jet charge that we refer to as the “dynamic jet charge.”
We present corresponding results for PYTHIA simulations of heavy ion PbPb collisions and find that, unlike for the standard jet charge, the discrimination power of the dynamic jet charge remains similar to that found in pp collisions, being largely unaffected by the significantly greater underlying activity
Summary
We present corresponding results for PYTHIA simulations of heavy ion PbPb collisions and find that, unlike for the standard jet charge, the discrimination power of the dynamic jet charge remains similar to that found in pp collisions, being largely unaffected by the significantly greater underlying activity. One might generalize other jet observables, such as jet angularities [40,41,42,43,44,45,46], by transforming the constant parameters that appear in their definitions to dynamic parameters If and how these dynamic jet charge definitions lead to increased discrimination power will be explored in future work. We see that there is good agreement between the PYTHIA simulation results and the ATLAS data
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