A search for anomalous production of events with three or more leptons using 19.5/fb of sqrt(s)=8 TeV LHC data

A model-independent search for physics beyond the standard model, in events with at least three leptons, is presented. The data sample corresponds to 19.5\,fb$^{-1}$ of integrated luminosity in pp collisions at $\sqrt{s}=8$ TeV collected by the CMS experiment at the LHC in 2012. Data are binned in exclusive channels characterized by lepton charge and flavor combinations, the magnitude of missing transverse energy and jet activity in the event, the invariant mass of opposite-sign lepton pairs consistent or inconsistent with the decay of a $Z$ boson, and the presence or absence of b quarks and taus. The observations are consistent with expectations from standard model processes. We characterize the sensitivity of this analysis to new physics by interpreting the results in various supersymmetric models that yield multilepton final states including ones with Higgs bosons arising from supersymmetric decays. Finally, we place a 95\% confidence level limit on the branching ratio for $t \rightarrow ch$ decays. We find that $\textrm{BR}(t \rightarrow ch) < 1.28\%$, corresponding to a bound on the top-charm flavor violating Higgs Yukawa couplings of $\sqrt{|\lambda_{tc}^h|^2 + |\lambda_{ct}^h|^2} < 0.21$. $~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~$ (*) This is a revised version of the original document (dated September 11, 2013). The current version corrects an error in the $t \rightarrow ch$ section where the previous version effectively quoted an upper limit on $\textrm{BR}(t \rightarrow ch) \times \textrm{BR}(\textrm{W} \rightarrow \ell \nu)$ instead of $\textrm{BR}(t \rightarrow ch)$.