2,269 research outputs found

    Single top measurements and the Vtb|V_{\rm tb}| extraction at the LHC

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    The CMS and ATLAS experiments have performed detailed studies on the electroweakly produced top quarks at the LHC. These studies range from accurate measurements of the cross section and Vtb|V_{\rm tb}| in different production modes to search for new interactions in the tWb\rm tWb vertex. Moreover, different properties of the top quark are precisely measured in this context. All measurements are consistent with the standard model and no sign of new physics is observed.Comment: Presented at TOP2014 7th International Workshop on Top Quark Physic

    Highlights of discussions on Top quark and Higgs Physics in CKM2018

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    In the 10^th International Workshop on the CKM Unitarity Triangle, the sessions of the High-p T flavor physics were devoted to the related topics in top quark physics, Higgs physics, semileptonic decays of B mesons and leptoquark searches. This notes summarizes the highlights of discussions on top quark and Higgs physics

    Transverse momentum spectra of b jets in pPb collisions at sqrt(s[NN]) = 5.02 TeV

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    We present a measurement of b jet transverse momentum (pt) spectra in proton-lead (pPb) collisions using a dataset corresponding to about 35 inverse nanobarns collected with the CMS detector at the LHC. Jets from b quark fragmentation are found by exploiting the long lifetime of hadrons containing a b quark through tagging methods using distributions of the secondary vertex mass and displacement. Extracted cross sections for b jets are scaled by the effective number of nucleon-nucleon collisions and are compared to a reference obtained from PYTHIA simulations of pp collisions. The PYTHIA-based estimate of the nuclear modification factor is found to be 1.22 +/- 0.15 (stat + syst pPb) +/- 0.27 (syst PYTHIA) averaged over all jets with pt between 55 and 400 GeV/c and with abs(eta[lab]) < 2. We also compare this result to predictions from models using perturbative calculations in quantum chromodynamics

    Search for quark contact interactions and extra spatial dimensions using dijet angular distributions in proton-proton collisions at sqrt(s) = 8 TeV

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    A search is presented for quark contact interactions and extra spatial dimensions in proton-proton collisions at sqrt(s) = 8 TeV using dijet angular distributions. The search is based on a data set corresponding to an integrated luminosity of 19.7 inverse femtobarns collected by the CMS detector at the CERN LHC. Dijet angular distributions are found to be in agreement with the perturbative QCD predictions that include electroweak corrections. Limits on the contact interaction scale from a variety of models at next-to-leading order in QCD corrections are obtained. A benchmark model in which only left-handed quarks participate is excluded up to a scale of 9.0 (11.7) TeV for destructive (constructive) interference at 95% confidence level. Lower limits between 5.9 and 8.4 TeV on the scale of virtual graviton exchange are extracted for the Arkani-Hamed--Dimopoulos--Dvali model of extra spatial dimensions

    Performance of photon reconstruction and identification with the CMS detector in proton-proton collisions at sqrt(s) = 8 TeV

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    A description is provided of the performance of the CMS detector for photon reconstruction and identification in proton-proton collisions at a centre-of-mass energy of 8 TeV at the CERN LHC. Details are given on the reconstruction of photons from energy deposits in the electromagnetic calorimeter (ECAL) and the extraction of photon energy estimates. The reconstruction of electron tracks from photons that convert to electrons in the CMS tracker is also described, as is the optimization of the photon energy reconstruction and its accurate modelling in simulation, in the analysis of the Higgs boson decay into two photons. In the barrel section of the ECAL, an energy resolution of about 1% is achieved for unconverted or late-converting photons from H to gamma gamma decays. Different photon identification methods are discussed and their corresponding selection efficiencies in data are compared with those found in simulated events

    Focus topics for the ECFA study on Higgs / Top / EW factories

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    In order to stimulate new engagement and trigger some concrete studies in areas where further work would be beneficial towards fully understanding the physics potential of an e+ee^+e^- Higgs / Top / Electroweak factory, we propose to define a set of focus topics. The general reasoning and the proposed topics are described in this document.Comment: v3: fixed spelling of two author

    Measurement of differential cross sections for top quark pair production using the lepton plus jets final state in proton-proton collisions at 13 TeV

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    National Science Foundation (U.S.

    Particle-flow reconstruction and global event description with the CMS detector

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    The CMS apparatus was identified, a few years before the start of the LHC operation at CERN, to feature properties well suited to particle-flow (PF) reconstruction: a highly-segmented tracker, a fine-grained electromagnetic calorimeter, a hermetic hadron calorimeter, a strong magnetic field, and an excellent muon spectrometer. A fully-fledged PF reconstruction algorithm tuned to the CMS detector was therefore developed and has been consistently used in physics analyses for the first time at a hadron collider. For each collision, the comprehensive list of final-state particles identified and reconstructed by the algorithm provides a global event description that leads to unprecedented CMS performance for jet and hadronic tau decay reconstruction, missing transverse momentum determination, and electron and muon identification. This approach also allows particles from pileup interactions to be identified and enables efficient pileup mitigation methods. The data collected by CMS at a centre-of-mass energy of 8 TeV show excellent agreement with the simulation and confirm the superior PF performance at least up to an average of 20 pileup interactions

    Search for heavy resonances decaying to a top quark and a bottom quark in the lepton+jets final state in proton–proton collisions at 13 TeV

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    info:eu-repo/semantics/publishe

    Pseudorapidity and transverse momentum dependence of flow harmonics in pPb and PbPb collisions

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    info:eu-repo/semantics/publishe
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