  The jet charge is an old observable that has proven uniquely useful for
discrimination of jets initiated by different flavors of light quarks, for
example. In this Letter, we propose an approach to understanding the jet charge
by establishing simple, robust assumptions that hold to good approximation
non-perturbatively, such as isospin conservation and large particle
multiplicity in the jets, forgoing any attempt at a perturbative analysis. From
these assumptions, the jet charge distribution with fixed particle multiplicity
takes the form of a Gaussian by the central limit theorem and whose mean and
variance are related to fractional-power moments of single particle energy
distributions. These results make several concrete predictions for the scaling
of the jet charge with the multiplicity, explaining many of the results already
in the literature, and new results we validate in Monte Carlo simulation.
