Knowing the charge of the parton initiating a light-quark jet could be
extremely useful both for testing aspects of the Standard Model and for
characterizing potential beyond-the-Standard-Model signals. We show that
despite the complications of hadronization and out-of-jet radiation such as
pile-up, a weighted sum of the charges of a jet's constituents can be used at
the LHC to distinguish among jets with different charges. Potential
applications include measuring electroweak quantum numbers of hadronically
decaying resonances or supersymmetric particles, as well as Standard Model
tests, such as jet charge in dijet events or in hadronically-decaying W bosons
in t-tbar events. We develop a systematically improvable method to calculate
moments of these charge distributions by combining multi-hadron fragmentation
functions with perturbative jet functions and pertubative evolution equations.
We show that the dependence on energy and jet size for the average and width of
the jet charge can be calculated despite the large experimental uncertainty on
fragmentation functions. These calculations can provide a validation tool for
data independent of Monte-Carlo fragmentation models.Comment: 5 pages, 6 figures; v2 published versio
