This paper presents a search for anomalous production of multiple low-energy leptons in association with a $W$ or $Z$ boson using events collected at the CDF experiment corresponding to $5.1$ fb${̂-1}$ of integrated luminosity. This search is sensitive to a wide range of topologies with low-momentum leptons, including those with the leptons near one another. The observed rates of production of additional electrons and muons are compared with the standard model predictions. No indications of phenomena beyond the standard model are found. A 95\% confidence level limit is presented on the production cross section for a benchmark model of supersymmetric hidden-valley Higgs production. Particle identification efficiencies are also provided to enable the calculation of limits on additional models.

A search is presented for anomalous production of events containing multiple low-energy leptons produced in association with a W or Z boson using the Collider Detector at Fermilab. The leptons are not required to be isolated, and the signature is therefore sensitive to a wide range of so-called "lepton jet" topologies. The search uses data corresponding to 5.1 fb--1 of integrated luminosity from pp ̄ collisions at a center-of-mass energy of s = 1.96 TeV. The observed events are compared with the standard model predictions in bins of additional electron and muon multiplicity. No indications are found of phenomena beyond the standard model. A 95% confidence level limit is presented on the production cross section for an example benchmark point of a dark-matter inspired model of supersymmetric hidden valley Higgs production. Object identification efficiencies are also provided in order to enable the calculation of limits on additional models.

This paper presents a search for anomalous production of multiple low-energy leptons in association with a W or Z boson using events collected at the CDF experiment corresponding to 5.1 fb−1 of integrated luminosity. This search is sensitive to a wide range of topologies with low-momentum leptons, including those with the leptons near one another. The observed rates of production of additional electrons and muons are compared with the standard model predictions. No indications of phenomena beyond the standard model are found. A 95% confidence level limit is presented on the production cross section for a benchmark model of supersymmetric hidden-valley Higgs production. Particle identification efficiencies are also provided to enable the calculation of limits on additional models.

The authors report a search for the anomalous production of events with multiple charged leptons in p{bar p} collisions at √s = 1.96 TeV using a data sample corresponding to an integrated luminosity of 346 pb−1 collected by the CDF II detector at the Fermilab Tevatron. The search is divided into three-lepton and four-or-more-lepton data samples. They observe six events in the three-lepton sample and zero events in the ≥4-lepton sample. Both numbers of events are consistent with standard model background expectations. Within the framework of an R-parity violating supergravity model, the results are interpreted as mass limits on the lightest neutralino ({bar {chi}}1°) and chargino ({bar {chi}}1{sup {+-}}) particles. For one particular choice of model parameters, the limits are M({bar {chi}}1°) > 110 GeV/c2 and M({bar {chi}}1{sup {+-}}) > 203 GeV/c2 at 95% confidence level; the variation of these mass limits with model parameters is presented.

The authors report a search for the anomalous production of events with multiple charged leptons in p{bar p} collisions at √s = 1.96 TeV using a data sample corresponding to an integrated luminosity of 346 pb−1 collected by the CDF II detector at the Fermilab Tevatron. The search is divided into three-lepton and four-or-more-lepton data samples. They observe six events in the three-lepton sample and zero events in the ≥4-lepton sample. Both numbers of events are consistent with standard model background expectations. Within the framework of an R-parity violating supergravity model, the results are interpreted as mass limits on the lightest neutralino ({bar {chi}}1°) and chargino ({bar {chi}}1{sup {+-}}) particles. For one particular choice of model parameters, the limits are M({bar {chi}}1°)> 110 GeV/c2 and M({bar {chi}}1{sup {+-}})> 203 GeV/c2 at 95% confidence level; the variation of these mass limits with model parameters is presented.

A search for physics beyond the standard model in events with at least three leptons is presented. The data sample, corresponding to an integrated luminosity of 19.5 inverse femtobarns of proton-proton collisions with center-of-mass energy sqrt(s) = 8 TeV, was collected by the CMS experiment at the LHC during 2012. The data are divided into exclusive categories based on the number of leptons and their flavor, the presence or absence of an opposite-sign, same-flavor lepton pair (OSSF), the invariant mass of the OSSF pair, the presence or absence of a tagged bottom-quark jet, the number of identified hadronically decaying tau leptons, and the magnitude of the missing transverse energy and of the scalar sum of jet transverse momenta. The numbers of observed events are found to be consistent with the expected numbers from standard model processes, and limits are placed on new-physics scenarios that yield multilepton final states. In particular, scenarios that predict Higgs boson production in the context of supersymmetric decay chains are examined. We also place a 95% confidence level upper limit of 1.3% on the branching fraction for the decay of a top quark to a charm quark and a Higgs boson (t to c H), which translates to a bound on the left- and right-handed top-charm flavor-violating Higgs Yukawa couplings, lambda[H, tc] and lambda[H, ct], respectively, of sqrt(abs(lambda[H, tc])2̂ + abs(lambda[H, ct])2̂)

We present a measurement of the production cross section for ZW and ZZ boson pairs in final states with a pair of charged leptons, from the decay of a Z boson, and at least two jets, from the decay of a W or Z boson, using the full sample of proton-antiproton collisions recorded with the CDF II detector at the Tevatron, corresponding to 8.9 fb(̂-1) of integrated luminosity. We increase the sensitivity to vector boson decays into pairs of quarks using a neural network discriminant that exploits the differences between the spatial spread of energy depositions and charged-particle momenta contained within the jet of particles originating from quarks and gluons. Additionally, we employ new jet energy corrections to Monte Carlo simulations that account for differences in the observed energy scales for quark and gluon jets. The number of signal events is extracted through a simultaneous fit to the dijet mass spectrum in three classes of events: events likely to contain jets with a heavy-quark decay, events likely to contain jets originating from light quarks, and events that fail these identification criteria. We determine the production cross section to be 2.5 +2.0 -1.0 pb (