2,218 research outputs found

    Monotop phenomenology at the Large Hadron Collider

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    We investigate new physics scenarios where systems comprised of a single top quark accompanied by missing transverse energy, dubbed monotops, can be produced at the LHC. Following a simplified model approach, we describe all possible monotop production modes via an effective theory and estimate the sensitivity of the LHC, assuming 20 fb−1^{-1} of collisions at a center-of-mass energy of 8 TeV, to the observation of a monotop state. Considering both leptonic and hadronic top quark decays, we show that large fractions of the parameter space are reachable and that new physics particles with masses ranging up to 1.5 TeV can leave hints within the 2012 LHC dataset, assuming moderate new physics coupling strengths.Comment: 17 pages, 12 figures, 3 table

    Probing top anomalous couplings at the LHC with trilepton signatures in the single top mode

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    We investigate trilepton final states to probe top anomalous couplings at the Large Hadron Collider. We focus on events originating from the associated production of a single top quark with a Z-boson, a channel sensitive to several flavor-changing neutral interactions of top and up/charm quarks. In particular, we explore a way to access simultaneously their anomalous couplings to Z-bosons and gluons and derive the discovery potential of trilepton final states to such interactions with 20 fb-1 of 8 TeV collisions. We show that effective coupling strengths of O(0.1-1) TeV-1 can be reached. Equivalently, branching fractions of top quarks into lighter quarks and gluons or Z-bosons can be constrained to be below O(0.1-1)%.Comment: 5 pages, 3 figures, 1 table; version accepted by PL

    Reception Test of Petals for the End Cap TEC+ of the CMS Silicon Strip Tracker

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    The silicon strip tracker of the CMS experiment has been completed and was inserted into the CMS detector in late 2007. The largest sub system of the tracker are its end caps, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted onto the TEC support structures. Each end cap consists of 144 such petals, which were built and fully qualified by several institutes across Europe. Fro

    Integration of the End Cap TEC+ of the CMS Silicon Strip Tracker

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    The silicon strip tracker of the CMS experiment has been completed and inserted into the CMS detector in late 2007. The largest sub-system of the tracker is its end cap system, comprising two large end caps (TEC) each containing 3200 silicon strip modules. To ease construction, the end caps feature a modular design: groups of about 20 silicon modules are placed on sub-assemblies called petals and these self-contained elements are then mounted into the TEC support structures. Each end cap consists of 144 petals, and the insertion of these petals into the end cap structure is referred to as TEC integration. The two end caps were integrated independently in Aachen (TEC+) and at CERN (TEC--). This note deals with the integration of TEC+, describing procedures for end cap integration and for quality control during testing of integrated sections of the end cap and presenting results from the testing

    Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV

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    Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio

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