352 research outputs found
A measurement of from the Gross-Llewellyn Smith Sum Rule
We extract a set of values for the Gross-Llewellyn Smith sum rule at
different values of 4-momentum transfer squared (), by combining revised
CCFR neutrino data with data from other neutrino deep-inelastic scattering
experiments for . A comparison with the order
theoretical predictions yields a determination of
at the scale of the Z-boson mass of . This measurement
provides a new and useful test of perturbative QCD at low , 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
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, , we obtain .Comment: 10 pages, Nevis Preprint #1498 (Submitted to Phys. Rev. Lett.
Epidemics on contact networks: a general stochastic approach
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
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
We present the result of a search for charged Higgs decays of the top quark,
produced in collisions at 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
18.70.7~pb, 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 collisions at TeV
The inclusive jet differential cross section has been measured for jet
transverse energies, , from 15 to 440 GeV, in the pseudorapidity region
0.10.7. The results are based on 19.5 pb 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 GeV is significantly
higher than current predictions based on O() perturbative QCD
calculations. Various possible explanations for the high- excess are
discussed.Comment: 8 pages with 2 eps uu-encoded figures Submitted to Physical Review
Letter
An improved method for measuring muon energy using the truncated mean of dE/dx
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
Limits on and Oscillations from a Precision Measurement of Neutrino-Nucleon Neutral Current Interactions
We present limits on and
oscillations based on a study of
inclusive 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 versus or charged current
interactions. The energies ranged from 30 to 500 GeV with a mean of
140 GeV. The minimum and maximum flight lengths are 0.9 km and 1.4 km
respectively. For oscillations, the lowest 90% confidence
upper limit in of is obtained at ~eV. This result is the most stringent limit to date for
eV. For oscillations, the lowest 90%
confidence upper limit in of is obtained at
~eV. This result is the most stringent limit to date for
eV, and also excludes at 90% confidence much of the
high region favored by the recent LSND observation.Comment: Revised version contains limit on oscillations as
well as limit on oscillations found in original. 15
pages, ReVTeX, 3 figures in uuencoded file, submitted to PR
An Improved Determination of From Neutrino-Nucleon Scattering
We present an improved determination of the proton structure functions
and from the CCFR -Fe deep inelastic scattering (DIS)
experiment. Comparisons to high-statistics charged-lepton scattering results
for from the NMC, E665, SLAC, and BCDMS experiments, after correcting
for quark-charge and heavy-target effects, indicate good agreement for
but some discrepancy at lower x. The evolution of the structure
functions yields the quantum chromodynamics (QCD) scale parameter
(exp.) MeV. This corresponds to a
value of the strong coupling constant at the scale of mass of the Z-boson of
and is one
of the most precise measurements of this quantity.Comment: 6 pages, RevTeX, Submitted to Phys. Rev. Let
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