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.
Definitions of super signal regions, along with predictions, observed data, and the observed 95% CL upper limits on the number of signal events contributing to each region ($N_{95}^\mathrm{max}$). The limits are given under assumptions of 0% and 15% for the uncertainty on the signal acceptance. All selection criteria as in the full analysis are applied. For regions with $N_\mathrm{j}=1$, $H_\mathrm{T}\equiv p_\mathrm{T}^\mathrm{jet}$.
Exclusion limits at 95% CL for direct gluino pair production, where the gluinos decay to light-flavor quarks ($\tilde{g}\to q\bar{q}\tilde{\chi}_1^0$). Signal cross sections are calculated at approximately NNLO+NNLL order in $\alpha_S$, assuming unity branching fraction to $q\bar{q}\tilde{\chi}_1^0$.
Exclusion limits at 95% CL for direct gluino pair production, where the gluinos decay to light-flavor quarks and either a $\tilde{\chi}_2^0$ that decays to $Z\tilde{\chi}_1^0$ (1/3 of the time), or a $\tilde{\chi}_1^\pm$ that decays to $W^\pm\tilde{\chi}_1^0$ (2/3 of the time). Signal cross sections are calculated at approximately NNLO+NNLL order in $\alpha_S$, assuming unity branching fraction to $q_i\bar{q}_j V\tilde{\chi}_1^0$.
Three of the most significant measured deviations from standard model predictions, the enhanced decay rate for B $\to$ D$^{(*)}\tau\nu$, hints of lepton universality violation in B $\to$ K$^{(*)}\ell\ell$ decays, and the anomalous magnetic moment of the muon, can be explained by the existence of leptoquarks (LQs) with large couplings to third-generation quarks and masses at the TeV scale. The existence of these states can be probed at the LHC in high energy proton-proton collisions. A novel search is presented for pair production of LQs coupled to a top quark and a muon using data at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb$^{-1}$, recorded by the CMS experiment. No deviation from the standard model prediction has been observed and scalar LQs decaying exclusively into t$\mu$ are excluded up to masses of 1420 GeV. The results of this search are combined with those from previous searches for LQ decays into t$\tau$ and b$\nu$, which excluded scalar LQs below masses of 900 and 1080 GeV. Vector LQs are excluded up to masses of 1190 GeV for all possible combinations of branching fractions to t$\mu$, t$\tau$ and b$\nu$. With this analysis, all relevant couplings of LQs with an electric charge of -1/3 to third-generation quarks are probed for the first time.
Distributions for $M_{LQ}^{rec}$ (category A) after applying the full selection. All backgrounds are normalized according to the post-fit nuisance parameters based on the corresponding SM cross sections.
Distributions for $S_{T}$ (category B) after applying the full selection and estimating the $t\overline{t}$ and DY+jets background contributions from data in category B. All backgrounds are normalized according to the post-fit nuisance parameters based on the corresponding SM cross sections.
Observed upper limits on the production cross section for pair production of LQs decaying into a top quark and a muon or a $\tau$ lepton at 95% CL in the $M_{LQ} - B(LQ \rightarrow t\mu)$ plane.
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