  If a new high-mass resonance is discovered at the Large Hadron Collider,
model-independent techniques to identify the production mechanism will be
crucial to understand its nature and effective couplings to Standard Model
particles. We present a powerful and model-independent method to infer the
initial state in the production of any high-mass color-singlet system by using
a tight veto on accompanying hadronic jets to divide the data into two mutually
exclusive event samples (jet bins). For a resonance of several hundred GeV, the
jet binning cut needed to discriminate quark and gluon initial states is in the
experimentally accessible range of several tens of GeV. It also yields
comparable cross sections for both bins, making this method viable already with
the small event samples available shortly after a discovery. Theoretically, the
method is made feasible by utilizing an effective field theory setup to compute
the jet cut dependence precisely and model independently and to systematically
control all sources of theoretical uncertainties in the jet binning, as well as
their correlations. We use a 750 GeV scalar resonance as an example to
demonstrate the viability of our method.
