Searches for new phenomena in events with jets and high values of the $M_{\mathrm{T2}}$ variable, including signatures with disappearing tracks, in proton-proton collisions at $\sqrt{s}=13~\mathrm{TeV}$

Searches for new phenomena are performed using events with jets and significant transverse momentum imbalance. In events with at least two jets, the transverse momentum imbalance is inferred through the $M_{\mathrm{T2}}$ variable. The results are based on a sample of proton-proton collisions collected with the CMS detector during the LHC Run II (2016-2018) and correspond to an integrated luminosity of $137~\mathrm{fb}^{-1}$ taken at a center-of-mass energy of $13~\mathrm{TeV}$. Two related searches are performed. The first is an inclusive search 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 $M_{\mathrm{T2}}$ for events with at least two jets, or the tranverse momentum of the jet for events with just one jet. The second is a search for disappearing tracks produced by new long-lived charged particles, decaying within the volume of the CMS tracking detector. No excess event yield is observed above the predicted standard model background, leading to exclusion limits on pair-produced gluinos and squarks in simplified models of $R$-parity conserving supersymmetry. Mass limits as high as $2250~\mathrm{GeV}$, $1770~\mathrm{GeV}$, $1260~\mathrm{GeV}$ and $1225~\mathrm{GeV}$ are obtained from the inclusive $M_{\mathrm{T2}}$ search for gluinos, light-flavor squarks, bottom squarks and top squarks, respectively. The search for disappearing tracks extends the gluino mass limit to as much as $2460~\mathrm{GeV}$, and the $\tilde{\chi}^{0}_{1}$ mass limit to as much as $2000~\mathrm{GeV}$, in models where the gluino can decay with equal probability to $\tilde{\chi}^{0}_{1}$, $\tilde{\chi}^{+}_{1}$, and $\tilde{\chi}^{-}_{1}$, and the $\tilde{\chi}^{\pm}_{1}$ are long-lived.