147 research outputs found

    Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

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    A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

    Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

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    Infection with Trypanosoma cruzi TcII and TcI in free-ranging population of lion tamarins (Leontopithecus spp): an 11-year follow-up

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    Here, we present a review of the dataset resulting from the 11-years follow-up of Trypanosoma cruziinfection in free-ranging populations of Leontopithecus rosalia(golden lion tamarin) andLeontopithecus chrysomelas(golden-headed lion tamarin) from distinct forest fragments in Atlantic Coastal Rainforest. Additionally, we present new data regarding T. cruziinfection of small mammals (rodents and marsupials) that live in the same areas as golden lion tamarins and characterisation at discrete typing unit (DTU) level of 77 of these isolates. DTU TcII was found to exclusively infect primates, while TcI infectedDidelphis aurita and lion tamarins. The majority ofT. cruziisolates derived from L. rosaliawere shown to be TcII (33 out 42) Nine T. cruziisolates displayed a TcI profile. Golden-headed lion tamarins demonstrated to be excellent reservoirs of TcII, as 24 of 26 T. cruziisolates exhibited the TcII profile. We concluded the following: (i) the transmission cycle of T. cruziin a same host species and forest fragment is modified over time, (ii) the infectivity competence of the golden lion tamarin population fluctuates in waves that peak every other year and (iii) both golden and golden-headed lion tamarins are able to maintain long-lasting infections by TcII and TcI

    Multiplicity and rapidity dependence of strange hadron production in pp, pPb, and PbPb collisions at the LHC

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    Multiplicity and rapidity dependence of strange hadron production in pp, pPb, and PbPb collisions at the LHC

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    Search for exotic decays of a Higgs boson into undetectable particles and one or more photons

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    Search for neutral MSSM Higgs bosons decaying into a pair of bottom quarks

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    Search for supersymmetry in events with a photon, a lepton, and missing transverse momentum in pp collisions at s=\sqrt s= 8 TeV

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    Search for neutral MSSM Higgs bosons decaying into a pair of bottom quarks

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    A search for neutral Higgs bosons decaying into a b-bbar quark pair and produced in association with at least one additional b quark is presented. This signature is sensitive to the Higgs sector of the minimal supersymmetric standard model (MSSM) with large values of the parameter tan(beta). The analysis is based on data from proton-proton collisions at a center-of-mass energy of 8 TeV collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 19.7 inverse femtobarns. The results are combined with a previous analysis based on 7 TeV data. No signal is observed. Stringent upper limits on the cross section times branching fraction are derived for Higgs bosons with masses up to 900 GeV, and the results are interpreted within different MSSM benchmark scenarios, m[h,max], m[h,mod+], m[h,mod-], light-stau and light-stop. Observed 95% confidence level upper limits on tan(beta), ranging from 14 to 50, are obtained in the m[h,mod+] benchmark scenario
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