27 research outputs found

    Measurement of the t(t)over-bar production cross section using events with one lepton and at least one jet in pp collisions at s√=13TeV

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    A measurement of the t (t) over bar production cross section at root s = 13 TeV is presented using proton-proton collisions, corresponding to an integrated luminosity of 2.2 fb(-1), collected with the CMS detector at the LHC. Final states with one isolated charged lepton (electron or muon) and at least one jet are selected and categorized according to the accompanying jet multiplicity. From a likelihood fit to the invariant mass distribution of the isolated lepton and a jet identified as coming from the hadronization of a bottom quark, the cross section is measured to be sigma(tt) = 888 +/- 2; (stat) (+26)(-28) (syst) +/- 20 (lumi) pb, in agreement with the standard model prediction. Using the expected dependence of the cross section on the pole mass of the top quark (m(t)), the value of m(t) is found to be 170:6 +/- 2:7 GeV.Peer reviewe

    Search for associated production of dark matter with a Higgs boson decaying to b(b)over-bar or gamma gamma at root s=13 TeV

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    Peer reviewe

    Measurement of the semileptonic t(t)over-bar + gamma production cross section in pp collisions at root s=8 TeV

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    Peer reviewe

    Measurement of the production cross section for Z gamma -> nu(nu)over-bar gamma in pp collisions at √s=7 TeV and limits on ZZ gamma and Z gamma gamma triple gauge boson couplings

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    This article is the pre-print version of the final published paper that is available from the link below.A measurement of the Z → vvÎł cross section in pp collisions at root s = 7TeV is presented, using data corresponding to an integrated luminosity of 5.0 fb-1 collected with the CMS detector. This measurement is based on the observation of events with an imbalance of transverse energy in excess of 130 GeV and a single photon in the absolute pseudorapidity range |n| < 1:4 with transverse energy above 145 GeV. The Z →vvÎł production cross section is measured to be 21.1±4.2 (stat:)±4.3 (syst:)±0.5 (lum:) fb, which agrees with the standard model prediction of 21.9±1.1 fb. The results are combined with the CMS measurement of Z production in the l+l- Îł final state (where l is an electron or a muon) to yield the most stringent limits to date on triple gauge boson couplings: |hZ3|< 2.7 x 10-3, |hZ4| < 1,3 x 10-5 for ZZÎł and |hÎł3| < 2.9 x10-3, |hÎł4| < 1.5 x 10-5 for Zγγ couplings

    Study of exclusive two-photon production of W+W- in pp collisions at √s=7 TeV and constraints on anomalous quartic gauge couplings

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    A search for exclusive or quasi-exclusive W+W- production by photon-photon interactions, pp -> p(*)W(+)W(-)p(*), at \/s = 7 TeV is reported using data collected by the CMS detector with an integrated luminosity of 5.05 fb(-1). Events are selected by requiring a mu(+/-)mu(-/+) vertex with no additional associated charged tracks and dilepton transverse momentum p(T)(mu(+/-)mu(-/+)) > 30 GeV. Two events passing all selection requirements are observed in the data, compared to a standard model expectation of 2.2 +/- 0.4 signal events with 0.84 +/- 0.15 background. The tail of the dilepton p(T) distribution is studied for deviations from the standard model. No events are observed with p(T) > 100 GeV. Model-independent upper limits are computed and compared to predictions involving anomalous quartic gauge couplings. The limits on the parameters a(0,c)(W)/A(2) with a dipole form factor and an energy cutoff A(cutoff) = 500 GeV are of the order of 10(-4)

    Search for associated production of a Z boson with a single top quark and for tZ flavour-changing interactions in pp collisions at root s=8 TeV

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    A search for the production of a single top quark in association with a Z boson is presented, both to identify the expected standard model process and to search for flavour-changing neutral current interactions. The data sample corresponds to an integrated luminosity of 19.7 fb−1 recorded by the CMS experiment at the LHC in proton-proton collisions at s√=8s=8 TeV. Final states with three leptons (electrons or muons) and at least one jet are investigated. An events yield compatible with tZq standard model production is observed, and the corresponding cross section is measured to be σ(pp → tZq → ℓΜbℓ+ℓ−q) = 10− 7+ 8 fb with a significance of 2.4 standard deviations. No presence of flavour-changing neutral current production of tZq is observed. Exclusion limits at 95% confidence level on the branching fractions of a top quark decaying to a Z boson and an up or a charm quark are found to be ℬ(t → Zu) < 0.022% and ℬ(t → Zc) < 0.049%

    Search for a Higgs boson in the mass range from 145 to 1000 GeV decaying to a pair of W or Z bosons

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    International Collaboration Boosting Open Science in Finland

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    The presentation of Kristiina Hormia-Poutanen in Fiesole Collection Development Retreat in Fiesole, Italy in April 4, 2019

    Comparison of the Z/<tex>\gamma</tex>∗+jetsto<tex>γ</tex>* + jets to <tex>\gamma</tex> + jets cross sections in pp collisions at <tex>\sqrt{s}$</tex>=8 TeV

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    Measurement of electroweak-induced production of W gamma with two jets in pp collisions at root s=8TeV and constraints on anomalous quartic gauge couplings

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    Abstract: A measurement of electroweak-induced production of W gamma and two jets is performed, where the W boson decays leptonically. The data used in the analysis correspond to an integrated luminosity of 19.7 fb(-1) collected by the CMS experiment in root s = 8TeV proton-proton collisions produced at the LHC. Candidate events are selected with exactly one muon or electron, missing transverse momentum, one photon, and two jets with large rapidity separation. An excess over the hypothesis of the standard model without electroweak production of W gamma with two jets is observed with a signi fi cance of 2.7 standard deviations. The cross section measured in the fi ducial region is 10.8 +/- 4.1(stat) +/- 3.4(syst) +/- 0. 3(lumi) fb, which is consistent with the standard model electroweak prediction. The total cross section for W gamma in association with two jets in the same fi ducial region is measured to be 23.2 +/- 4.3(stat) +/- 1.7(syst) +/- 0.6(lumi) fb, which is consistent with the standard model prediction from the combination of electroweakand quantum chromodynamics-induced processes. No deviations are observed from the standard model predictions and experimental limits on anomalous quartic gauge couplings integral M,0- 7 /Lambda(4), integral T,0- 2 /Lambda(4), and integral T,5-7/Lambda(4) are set at 95% con fi dence level
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