Calculating the Charge of a Jet

Abstract

Jet charge has played an important role in experimentally testing the Parton Model and the Standard Model, and has many potential LHC applications. The energy-weighted charge of a jet is not an infrared-safe quantity, so hadronization must be taken into account. Here we develop the formalism to calculate it, cleanly separating the nonperturbative from the perturbative physics, which we compute at one-loop order. We first study the average and width of the jet charge distribution, for which the nonperturbative input is related to (dihadron) fragmentation functions. In an alternative and novel approach, we consider the full nonperturbative jet charge distribution and calculate its evolution and jet algorithm corrections, which has a natural Monte Carlo-style implementation. Our numerical results are compared to Pythia and agree well in almost all cases. This calculation can directly be extended to similar track-based observables, such as the total track momentum generated by an energetic parton.