  Two related searches for phenomena beyond the standard model (BSM) are
performed using events with hadronic jets and significant transverse momentum
imbalance. The results are based on a sample of proton-proton collisions at a
center-of-mass energy of 13 TeV, collected by the CMS experiment at the LHC in
2016-2018 and corresponding to an integrated luminosity of 137 fb$^{-1}$. The
first search is inclusive, based on signal regions defined by the hadronic
energy in the event, the jet multiplicity, the number of jets identified as
originating from bottom quarks, and the value of the kinematic variable
$M_\mathrm{T2}$ for events with at least two jets. For events with exactly one
jet, the transverse momentum of the jet is used instead. The second search
looks in addition for disappearing tracks produced by BSM long-lived charged
particles that decay within the volume of the tracking detector. No excess
event yield is observed above the predicted standard model background. This is
used to constrain a range of BSM models that predict the following: the pair
production of gluinos and squarks in the context of supersymmetry models
conserving $R$-parity, with or without intermediate long-lived charginos
produced in the decay chain; the resonant production of a colored scalar state
decaying to a massive Dirac fermion and a quark; or the pair production of
scalar and vector leptoquarks each decaying to a neutrino and a top, bottom, or
light-flavor quark. In most of the cases, the results obtained are the most
stringent constraints to date.
