Searches for physics beyond the standard model with the MT2 variable in hadronic final states with and without disappearing tracks in proton-proton collisions at s=13Te

Two related searches for phenomena beyond the standard model (BSM) areperformed using events with hadronic jets and significant transversemomentum imbalance. The results are based on a sample of proton-protoncollisions at a center-of-mass energy of 13Te, collected by the CMSexperiment at the LHC in 2016-2018 and corresponding to an integratedluminosity of 137fb-1. The first search is inclusive, based on signalregions defined by the hadronic energy in the event, the jetmultiplicity, the number of jets identified as originating from bottomquarks, and the value of the kinematic variable MT2 for events with atleast two jets. For events with exactly one jet, the transverse momentumof the jet is used instead. The second search looks in addition fordisappearing tracks produced by BSM long-lived charged particles thatdecay within the volume of the tracking detector. No excess event yieldis observed above the predicted standard model background. This is usedto constrain a range of BSM models that predict the following: the pairproduction of gluinos and squarks in the context of supersymmetry modelsconserving R-parity, with or without intermediate long-lived charginosproduced in the decay chain; the resonant production of a colored scalarstate decaying to a massive Dirac fermion and a quark; or the pairproduction of scalar and vector leptoquarks each decaying to a neutrinoand a top, bottom, or light-flavor quark. In most of the cases, theresults obtained are the most stringent constraints to date.