  The LHC is actively searching for narrow dijet resonances corresponding to
physics beyond the Standard Model. Among the many resonances that have been
postulated (e.g., colored vectors, scalars, and fermions) one that would have a
particularly large production rate at the LHC would be a scalar diquark
produced in the s-channel via fusion of two valence quarks. In previous work,
we introduced a color discriminant variable that distinguishes among various
dijet resonances, drawing on measurements of the dijet resonance mass, total
decay width and production cross-section. Here, we show that this
model-independent method applies well to color-triplet and color-sextet scalar
diquarks, distinguishing them clearly from other candidate resonances. We also
introduce a more transparent theoretical formulation of the color discriminant
variable that highlights its relationship to the branching ratios of the
resonance into incoming and outgoing partons and to the properties of those
partons. While the original description of the color discriminant variable
remains convenient for phenomenological use upon discovery of a new resonance,
the new formulation makes it easier to predict the value of the variable for a
given class of resonance.
