A search is performed for the lepton number violating decay B+→h−μ+μ+, where h− represents a K− or a π−, using an integrated luminosity of 36 pb−1 of data collected with the LHCb detector. The decay is forbidden ...
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A search is performed for the lepton number violating decay B+→h−μ+μ+, where h− represents a K− or a π−, using an integrated luminosity of 36 pb−1 of data collected with the LHCb detector. The decay is forbidden in the standard model but allowed in models with a Majorana neutrino. No signal is observed in either channel and limits of B(B+→K−μ+μ+)<5.4×10−8 and B(B+→π−μ+μ+)<5.8×10−8 are set at the 95% confidence level. These improve the previous best limits by factors of 40 and 30, respectively.
Randomly distributed offset charges affect the nonlinear current-voltage property via the fluctuation of the threshold voltage above which the current flows in an array of a Coulomb blockade (CB). We analytically deri...
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Randomly distributed offset charges affect the nonlinear current-voltage property via the fluctuation of the threshold voltage above which the current flows in an array of a Coulomb blockade (CB). We analytically derive the distribution of the threshold voltage for a model of one-dimensional locally coupled CB arrays and propose a general relationship between conductance and distribution. In addition, we show that the distribution for a long array is equivalent to the distribution of the number of upward steps for aligned objects of different heights. The distribution satisfies a novel Fokker-Planck equation corresponding to active Brownian motion. The feature of the distribution is clarified by comparing it with the Wigner and Ornstein-Uhlenbeck processes. It is not restricted to the CB model but is instructive in statistical physics generally.
A search is presented for direct top squark pair production in final states with one isolated electron or muon, jets, and missing transverse momentum in proton-proton collisions at s=7 TeV. The measurement is based o...
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A search is presented for direct top squark pair production in final states with one isolated electron or muon, jets, and missing transverse momentum in proton-proton collisions at s=7 TeV. The measurement is based on 4.7 fb−1 of data collected with the ATLAS detector at the LHC. Each top squark is assumed to decay to a top quark and the lightest supersymmetric particle (LSP). The data are found to be consistent with standard model expectations. Top squark masses between 230 GeV and 440 GeV are excluded with 95% confidence for massless LSPs, and top squark masses around 400 GeV are excluded for LSP masses up to 125 GeV.
A search for direct pair production of supersymmetric top squarks (t˜1) is presented, assuming the t˜1 decays into a top quark and the lightest supersymmetric particle, χ˜10, and that both top quarks decay to purely ...
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A search for direct pair production of supersymmetric top squarks (t˜1) is presented, assuming the t˜1 decays into a top quark and the lightest supersymmetric particle, χ˜10, and that both top quarks decay to purely hadronic final states. A total of 16 (4) events are observed compared to a predicted standard model background of 13.5−3.6+3.7(4.4−1.3+1.7) events in two signal regions based on ∫Ldt=4.7 fb−1 of pp collision data taken at s=7 TeV with the ATLAS detector at the LHC. An exclusion region in the t˜1 versus χ˜10 mass plane is evaluated: 370
A measurement of spin correlation in tt¯ production is reported using data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 2.1 fb−1. Candidate events are selected in th...
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A measurement of spin correlation in tt¯ production is reported using data collected with the ATLAS detector at the LHC, corresponding to an integrated luminosity of 2.1 fb−1. Candidate events are selected in the dilepton topology with large missing transverse energy and at least two jets. The difference in azimuthal angle between the two charged leptons in the laboratory frame is used to extract the correlation between the top and antitop quark spins. In the helicity basis the measured degree of correlation corresponds to Ahelicity=0.40−0.08+0.09, in agreement with the next-to-leading-order standard model prediction. The hypothesis of zero spin correlation is excluded at 5.1 standard deviations.
This Letter describes a model-independent search for the production of new resonant states in photon+jet events in 2.11 fb−1 of proton-proton collisions at s=7 TeV. We compare the photon+jet mass distribution to a b...
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This Letter describes a model-independent search for the production of new resonant states in photon+jet events in 2.11 fb−1 of proton-proton collisions at s=7 TeV. We compare the photon+jet mass distribution to a background model derived from data and find consistency with the background-only hypothesis. Given the lack of evidence for a signal, we set 95% credibility level limits on generic Gaussian-shaped signals and on a benchmark excited-quark (q*) model, excluding 2 TeV Gaussian resonances with cross section times branching fraction times acceptance times efficiency near 5 fb and excluding q* masses below 2.46 TeV, respectively.
This Letter presents a search for magnetic monopoles with the ATLAS detector at the CERN Large Hadron Collider using an integrated luminosity of 2.0 fb−1 of pp collisions recorded at a center-of-mass energy of s=7 T...
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This Letter presents a search for magnetic monopoles with the ATLAS detector at the CERN Large Hadron Collider using an integrated luminosity of 2.0 fb−1 of pp collisions recorded at a center-of-mass energy of s=7 TeV. No event is found in the signal region, leading to an upper limit on the production cross section at 95% confidence level of 1.6/ϵ fb for Dirac magnetic monopoles with the minimum unit magnetic charge and with mass between 200 GeV and 1500 GeV, where ϵ is the monopole reconstruction efficiency. The efficiency ϵ is high and uniform in the fiducial region given by pseudorapidity |η|<1.37 and transverse kinetic energy 600–700
A search for the Higgs boson has been performed in the H→WW(*)→ℓ+νℓ−ν¯ channel (ℓ=e/μ) with an integrated luminosity of 2.05 fb−1 of pp collisions at s=7 TeV collected with the ATLAS detector at the Large ...
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A search for the Higgs boson has been performed in the H→WW(*)→ℓ+νℓ−ν¯ channel (ℓ=e/μ) with an integrated luminosity of 2.05 fb−1 of pp collisions at s=7 TeV collected with the ATLAS detector at the Large Hadron Collider. No significant excess of events over the expected background is observed and limits on the Higgs boson production cross section are derived for a Higgs boson mass in the range 110 GeV
A QCD analysis is reported of ATLAS data on inclusive W± and Z boson production in pp collisions at the LHC, jointly with ep deep-inelastic scattering data from HERA. The ATLAS data exhibit sensitivity to the lig...
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A QCD analysis is reported of ATLAS data on inclusive W± and Z boson production in pp collisions at the LHC, jointly with ep deep-inelastic scattering data from HERA. The ATLAS data exhibit sensitivity to the light quark sea composition and magnitude at Bjorken x∼0.01. Specifically, the data support the hypothesis of a symmetric composition of the light quark sea at low x. The ratio of the strange-to-down sea quark distributions is determined to be 1.00−0.28+0.25 at absolute four-momentum transfer squared Q2=1.9 GeV2 and x=0.023.
A search for the decay of a light Higgs boson (120–140 GeV) to a pair of weakly interacting, long-lived particles in 1.94 fb−1 of proton-proton collisions at s=7 TeV recorded in 2011 by the ATLAS detector is presen...
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A search for the decay of a light Higgs boson (120–140 GeV) to a pair of weakly interacting, long-lived particles in 1.94 fb−1 of proton-proton collisions at s=7 TeV recorded in 2011 by the ATLAS detector is presented. The search strategy requires that both long-lived particles decay inside the muon spectrometer. No excess of events is observed above the expected background and limits on the Higgs boson production times branching ratio to weakly interacting, long-lived particles are derived as a function of the particle proper decay length.
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