  The diverse and distinct collider phenomenology of color-sextet scalars
motivates thorough investigation of their effective couplings to the Standard
Model at the LHC. Some of the more unique sextet signals involve not only jets
but also leptons. In previous work, we proposed an LHC search for color-sextet
scalars in a channel with jets and a hard opposite-sign lepton pair, which
results from a dimension-six coupling. In this sequel we study the counterpart
processes with neutrinos, which produce jets in association with missing
transverse energy ($E_{\text{T}}^{\text{miss}}$) in addition to possible
leptons. We consider multiple search channels, including both single and pair
sextet production, all characterized by significant missing energy and some
featuring distinctive kinematic features. Our multifaceted study consists of
three reinterpreted existing searches and a joint-likelihood analysis designed
by us to maximize HL-LHC sensitivity to single sextet production. We show that
our dedicated strategy in the jets + lepton + $E_{\text{T}}^{\text{miss}}$
channel can supersede today's limits from reinterpreted searches, and we make
sensitivity projections for the HL-LHC. Altogether, our analysis can exclude
sextet scalars lighter than 4.4 TeV or probe effective cutoffs as high as 16.8
TeV.
