525 research outputs found

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

    Get PDF
    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

    Observation of tW production in the single-lepton channel in pp collisions at root s=13 TeV

    Get PDF
    A measurement of the cross section of the associated production of a single top quark and a W boson in final states with a muon or electron and jets in proton-proton collisions at root s = 13 TeV is presented. The data correspond to an integrated luminosity of 36 fb(-1) collected with the CMS detector at the CERN LHC in 2016. A boosted decision tree is used to separate the tW signal from the dominant t (t) over bar background, whilst the subleading W+jets and multijet backgrounds are constrained using data-based estimates. This result is the first observation of the tW process in final states containing a muon or electron and jets, with a significance exceeding 5 standard deviations. The cross section is determined to be 89 +/- 4 (stat) +/- 12 (syst) pb, consistent with the standard model.Peer reviewe

    Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

    Get PDF
    Peer reviewe

    Measurement of the top quark mass using events with a single reconstructed top quark in pp collisions at root s=13 TeV

    Get PDF
    Abstract:A measurement of the top quark mass is performed using a data sample en-riched with single top quark events produced in thetchannel. The study is based on proton-proton collision data, corresponding to an integrated luminosity of 35.9 fb−1, recorded at√s= 13TeV by the CMS experiment at the LHC in 2016. Candidate events are selectedby requiring an isolated high-momentum lepton (muon or electron) and exactly two jets,of which one is identified as originating from a bottom quark. Multivariate discriminantsare designed to separate the signal from the background. Optimized thresholds are placedon the discriminant outputs to obtain an event sample with high signal purity. The topquark mass is found to be172.13+0.76−0.77GeV, where the uncertainty includes both the sta-tistical and systematic components, reaching sub-GeV precision for the first time in thisevent topology. The masses of the top quark and antiquark are also determined separatelyusing the lepton charge in the final state, from which the mass ratio and difference aredetermined to be0.9952+0.0079−0.0104and0.83+1.79−1.35GeV, respectively. The results are consistentwithCPTinvariance

    Search for a heavy Higgs boson decaying into two lighter Higgs bosons in the tau tau bb final state at 13 TeV

    Get PDF
    A search for a heavy Higgs boson H decaying into the observed Higgs boson h with a mass of 125 GeV and another Higgs boson h(S) is presented. The h and h(S) bosons are required to decay into a pair of tau leptons and a pair of b quarks, respectively. The search uses a sample of proton-proton collisions collected with the CMS detector at a center-of-mass energy of 13TeV, corresponding to an integrated luminosity of 137 fb(-1). Mass ranges of 240-3000 GeV for m(H) and 60-2800 GeV for m(hS) are explored in the search. No signal has been observed. Model independent 95% confidence level upper limits on the product of the production cross section and the branching fractions of the signal process are set with a sensitivity ranging from 125 fb (for m(H) = 240 GeV) to 2.7 fb (for m(H) = 1000 GeV). These limits are compared to maximally allowed products of the production cross section and the branching fractions of the signal process in the next-to-minimal supersymmetric extension of the standard model.Peer reviewe

    Performance of CMS Endcap Precision Timing Sensors

    No full text
    The Large Hadron Collider, a particle accelerator in Geneva, Switzerland, willenter its High Luminosity (HL) phase, whose upgrade has already started. Thisphase will include an increase in particle collisions, achieving instantaneousluminosities of 5 to 7 times the nominal luminosity, 1 × 10 34 cm −2 s −1. Thisincrease gives more opportunities for rare processes to come to light, howeverit also means that there is more overlapping particle interactions, calledpileup, in the detectors. To address this added pileup, the Compact MuonSolenoid (CMS) detector at the LHC will install a new precision timing detector,the MIP Timing Detector (MTD), as part of the upgrades for the HL-LHC. Thesensors comprising the endcap section of the MTD are silicon low gain avalanchedetectors (LGADs). From extensive tests at the Fermilab test beam facility, ithas been shown that prototypes of these sensors perform in accordance to ourexpectations and requirements for the MTD. Specifically, these sensors havedemonstrated a timing resolution within 30-40 picoseconds

    Performance of CMS Endcap Precision Timing Sensors

    No full text
    The Large Hadron Collider, a particle accelerator in Geneva, Switzerland, will enter its High Luminosity (HL) phase, whose upgrade has already started. This phase will include an increase in particle collisions, achieving instantaneous luminosities of 5 to 7 times the nominal luminosity, 1 × 10341~\times~10^{34}~cm2^{-2}s1^{-1}. This increase gives more opportunities for rare processes to come to light, however it also means that there is more overlapping particle interactions, called pileup, in the detectors. To address this added pileup, the Compact Muon Solenoid (CMS) detector at the LHC will install a new precision timing detector, the MIP Timing Detector (MTD), as part of the upgrades for the HL-LHC. The sensors comprising the endcap section of the MTD are silicon low gain avalanche detectors (LGADs). From extensive tests at the Fermilab test beam facility, it has been shown that prototypes of these sensors perform in accordance to our expectations and requirements for the MTD. Specifically, these sensors have demonstrated a timing resolution within 30-40 picoseconds

    NA62 electronics barracks access 2017

    Get PDF
    Access to the cavern was required during a break in the 2017 data taking. Pictures from 18-07-17, focusing on the electronics barracks and some safety equipment

    Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s\sqrt{s} = 5.02 TeV

    No full text
    International audienceThe inclusive jet cross section is measured as a function of jet transverse momentum pTp_\mathrm{T} and rapidity yy. The measurement is performed using proton-proton collision data at s\sqrt{s} = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb1^{-1}. The jets are reconstructed with the anti-kTk_\mathrm{T} algorithm using a distance parameter of RR = 0.4, within the rapidity interval y\lvert y\rvert<\lt 2, and across the kinematic range 0.06 <\ltpTp_\mathrm{T}<\lt 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling αS\alpha_\mathrm{S}

    Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s\sqrt{s} = 5.02 TeV

    No full text
    International audienceThe inclusive jet cross section is measured as a function of jet transverse momentum pTp_\mathrm{T} and rapidity yy. The measurement is performed using proton-proton collision data at s\sqrt{s} = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb1^{-1}. The jets are reconstructed with the anti-kTk_\mathrm{T} algorithm using a distance parameter of RR = 0.4, within the rapidity interval y\lvert y\rvert<\lt 2, and across the kinematic range 0.06 <\ltpTp_\mathrm{T}<\lt 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling αS\alpha_\mathrm{S}
    corecore