399 research outputs found

    A measurement of alphas(Q2)alpha_s(Q^2) from the Gross-Llewellyn Smith Sum Rule

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    We extract a set of values for the Gross-Llewellyn Smith sum rule at different values of 4-momentum transfer squared (Q2Q^{2}), by combining revised CCFR neutrino data with data from other neutrino deep-inelastic scattering experiments for 1<Q2<15GeV2/c21 < Q^2 < 15 GeV^2/c^2. A comparison with the order αs3\alpha^{3}_{s} theoretical predictions yields a determination of αs\alpha_{s} at the scale of the Z-boson mass of 0.114±.012.0090.114 \pm^{.009}_{.012}. This measurement provides a new and useful test of perturbative QCD at low Q2Q^2, because of the low uncertainties in the higher order calculations.Comment: 4 pages, 4 figure

    A Precise Measurement of the Weak Mixing Angle in Neutrino-Nucleon Scattering

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    We report a precise measurement of the weak mixing angle from the ratio of neutral current to charged current inclusive cross-sections in deep-inelastic neutrino-nucleon scattering. The data were gathered at the CCFR neutrino detector in the Fermilab quadrupole-triplet neutrino beam, with neutrino energies up to 600 GeV. Using the on-shell definition, sin2θW1MW2MZ2{\rm sin ^2\theta_W} \equiv 1 - \frac{{\rm M_W} ^2}{{\rm M_Z} ^2}, we obtain sin2θW=0.2218±0.0025(stat.)±0.0036(exp.syst.)±0.0040(model){\rm sin ^2\theta_W} = 0.2218 \pm 0.0025 ({\rm stat.}) \pm 0.0036 ({\rm exp.\: syst.}) \pm 0.0040 ({\rm model}).Comment: 10 pages, Nevis Preprint #1498 (Submitted to Phys. Rev. Lett.

    Epidemics on contact networks: a general stochastic approach

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    Dynamics on networks is considered from the perspective of Markov stochastic processes. We partially describe the state of the system through network motifs and infer any missing data using the available information. This versatile approach is especially well adapted for modelling spreading processes and/or population dynamics. In particular, the generality of our systematic framework and the fact that its assumptions are explicitly stated suggests that it could be used as a common ground for comparing existing epidemics models too complex for direct comparison, such as agent-based computer simulations. We provide many examples for the special cases of susceptible-infectious-susceptible (SIS) and susceptible-infectious-removed (SIR) dynamics (e.g., epidemics propagation) and we observe multiple situations where accurate results may be obtained at low computational cost. Our perspective reveals a subtle balance between the complex requirements of a realistic model and its basic assumptions.Comment: Main document: 16 pages, 7 figures. Electronic Supplementary Material (included): 6 pages, 1 tabl

    Nuclear Structure Functions in the Large x Large Q^2 Kinematic Region in Neutrino Deep Inelastic Scattering

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    Data from the CCFR E770 Neutrino Deep Inelastic Scattering (DIS) experiment at Fermilab contain events with large Bjorken x (x>0.7) and high momentum transfer (Q^2>50 (GeV/c)^2). A comparison of the data with a model based on no nuclear effects at large x, shows a significant excess of events in the data. Addition of Fermi gas motion of the nucleons in the nucleus to the model does not explain the excess. Adding a higher momentum tail due to the formation of ``quasi-deuterons'' makes some improvement. An exponentially falling F_2 \propto e^-s(x-x_0) at large x, predicted by ``multi-quark clusters'' and ``few-nucleon correlations'', can describe the data. A value of s=8.3 \pm 0.7(stat.)\pm 0.7(sys.) yields the best agreement with the data.Comment: 4 pages, 4 figures, 1 table. Sibmitted to PR

    Search for charged Higgs decays of the top quark using hadronic tau decays

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    We present the result of a search for charged Higgs decays of the top quark, produced in ppˉp\bar{p} collisions at s=\surd s = 1.8 TeV. When the charged Higgs is heavy and decays to a tau lepton, which subsequently decays hadronically, the resulting events have a unique signature: large missing transverse energy and the low-charged-multiplicity tau. Data collected in the period 1992-1993 at the Collider Detector at Fermilab, corresponding to 18.7±\pm0.7~pb1^{-1}, exclude new regions of combined top quark and charged Higgs mass, in extensions to the standard model with two Higgs doublets.Comment: uuencoded, gzipped tar file of LaTeX and 6 Postscript figures; 11 pp; submitted to Phys. Rev.

    Inclusive jet cross section in pˉp{\bar p p} collisions at s=1.8\sqrt{s}=1.8 TeV

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    The inclusive jet differential cross section has been measured for jet transverse energies, ETE_T, from 15 to 440 GeV, in the pseudorapidity region 0.1η\leq | \eta| \leq 0.7. The results are based on 19.5 pb1^{-1} of data collected by the CDF collaboration at the Fermilab Tevatron collider. The data are compared with QCD predictions for various sets of parton distribution functions. The cross section for jets with ET>200E_T>200 GeV is significantly higher than current predictions based on O(αs3\alpha_s^3) perturbative QCD calculations. Various possible explanations for the high-ETE_T excess are discussed.Comment: 8 pages with 2 eps uu-encoded figures Submitted to Physical Review Letter

    Use of attribute association error probability estimates to evaluate quality of medical record geocodes

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    BACKGROUND: The utility of patient attributes associated with the spatiotemporal analysis of medical records lies not just in their values but also the strength of association between them. Estimating the extent to which a hierarchy of conditional probability exists between patient attribute associations such as patient identifying fields, patient and date of diagnosis, and patient and address at diagnosis is fundamental to estimating the strength of association between patient and geocode, and patient and enumeration area. We propose a hierarchy for the attribute associations within medical records that enable spatiotemporal relationships. We also present a set of metrics that store attribute association error probability (AAEP), to estimate error probability for all attribute associations upon which certainty in a patient geocode depends. METHODS: A series of experiments were undertaken to understand how error estimation could be operationalized within health data and what levels of AAEP in real data reveal themselves using these methods. Specifically, the goals of this evaluation were to (1) assess if the concept of our error assessment techniques could be implemented by a population-based cancer registry; (2) apply the techniques to real data from a large health data agency and characterize the observed levels of AAEP; and (3) demonstrate how detected AAEP might impact spatiotemporal health research. RESULTS: We present an evaluation of AAEP metrics generated for cancer cases in a North Carolina county. We show examples of how we estimated AAEP for selected attribute associations and circumstances. We demonstrate the distribution of AAEP in our case sample across attribute associations, and demonstrate ways in which disease registry specific operations influence the prevalence of AAEP estimates for specific attribute associations. CONCLUSIONS: The effort to detect and store estimates of AAEP is worthwhile because of the increase in confidence fostered by the attribute association level approach to the assessment of uncertainty in patient geocodes, relative to existing geocoding related uncertainty metrics

    Limits on νμ(νˉμ)ντ(νˉτ)\nu_\mu(\bar{\nu}_\mu)\to\nu_\tau(\bar{\nu}_\tau) and νμ(νˉμ)νe(νˉe)\nu_\mu(\bar{\nu}_\mu)\to\nu_e(\bar{\nu}_e) Oscillations from a Precision Measurement of Neutrino-Nucleon Neutral Current Interactions

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    We present limits on νμ(νˉμ)ντ(νˉτ)\nu_\mu(\bar{\nu}_\mu)\to\nu_\tau(\bar{\nu}_\tau) and νμ(νˉμ)νe(νˉe)\nu_\mu(\bar{\nu}_\mu)\to\nu_e(\bar{\nu}_e) oscillations based on a study of inclusive νN\nu N interactions performed using the CCFR massive coarse grained detector in the FNAL Tevatron Quadrupole Triplet neutrino beam. The sensitivity to oscillations is from the difference in the longitudinal energy deposition pattern of νμN\nu_\mu N versus ντN\nu_\tau N or νeN\nu_e N charged current interactions. The νμ\nu_\mu energies ranged from 30 to 500 GeV with a mean of 140 GeV. The minimum and maximum νμ\nu_\mu flight lengths are 0.9 km and 1.4 km respectively. For νμντ\nu_\mu\to\nu_\tau oscillations, the lowest 90% confidence upper limit in sin22α\sin^22\alpha of 2.7×1032.7\times 10^{-3} is obtained at Δm250\Delta m^2\sim50~eV2^2. This result is the most stringent limit to date for 25<Δm2<9025<\Delta m^2<90 eV2^2. For νμνe\nu_\mu\to\nu_e oscillations, the lowest 90% confidence upper limit in sin22α\sin^22\alpha of 1.9×1031.9\times 10^{-3} is obtained at Δm2350\Delta m^2\sim350~eV2^2. This result is the most stringent limit to date for 250<Δm2<450250<\Delta m^2<450 eV2^2, and also excludes at 90% confidence much of the high Δm2\Delta m^2 region favored by the recent LSND observation.Comment: Revised version contains limit on νμνe\nu_\mu\to\nu_e oscillations as well as limit on νμντ\nu_\mu\to\nu_\tau oscillations found in original. 15 pages, ReVTeX, 3 figures in uuencoded file, submitted to PR

    An improved method for measuring muon energy using the truncated mean of dE/dx

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    The measurement of muon energy is critical for many analyses in large Cherenkov detectors, particularly those that involve separating extraterrestrial neutrinos from the atmospheric neutrino background. Muon energy has traditionally been determined by measuring the specific energy loss (dE/dx) along the muon's path and relating the dE/dx to the muon energy. Because high-energy muons (E_mu > 1 TeV) lose energy randomly, the spread in dE/dx values is quite large, leading to a typical energy resolution of 0.29 in log10(E_mu) for a muon observed over a 1 km path length in the IceCube detector. In this paper, we present an improved method that uses a truncated mean and other techniques to determine the muon energy. The muon track is divided into separate segments with individual dE/dx values. The elimination of segments with the highest dE/dx results in an overall dE/dx that is more closely correlated to the muon energy. This method results in an energy resolution of 0.22 in log10(E_mu), which gives a 26% improvement. This technique is applicable to any large water or ice detector and potentially to large scintillator or liquid argon detectors.Comment: 12 pages, 16 figure
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