59 research outputs found
Results from a Fermilab neutrino beam dump experiment
The flux of prompt neutrinos from a beam dump has been measured in an experiment at the Fermi National Accelerator Laboratory (E613). Assuming that the charm production has a linear dependence on atomic number and varies as (1ââĂâ)5 eâ2mT, a model dependent cross section of 27±5ÎŒb/nucleon can be derived. For neutrino energies greater than 20 GeV, the flux of electron neutrinos with respect to muon neutrinos is 0.78±0.19. For neutrinos with energy greater than 30 GeV and pâ greater than 0.2, the flux of ÎœÌu compared to ΜΌ is 0.96±0.22.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87363/2/100_1.pd
Prompt Neutrino Results from Fermi Lab
Results from a Fermi lab experiment to study prompt neutrino production are presented. Assuming the prompt neutrinos come from the decay of charmed mesons we find a total DD production cross section of approx. 20 Όb/nucleon, in good agreement with previous CERN results. We find a Μ/Μ ratio and a Μe/ΜΌ of approx. 1.0. The energy and pT spectra of the prompt neutrinos are consistent with those expected from DD production. Limits on the production of supersymmetric particles have also been obtained.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87356/2/262_1.pd
Measurement of inclusive D*+- and associated dijet cross sections in photoproduction at HERA
Inclusive photoproduction of D*+- mesons has been measured for photon-proton
centre-of-mass energies in the range 130 < W < 280 GeV and a photon virtuality
Q^2 < 1 GeV^2. The data sample used corresponds to an integrated luminosity of
37 pb^-1. Total and differential cross sections as functions of the D*
transverse momentum and pseudorapidity are presented in restricted kinematical
regions and the data are compared with next-to-leading order (NLO) perturbative
QCD calculations using the "massive charm" and "massless charm" schemes. The
measured cross sections are generally above the NLO calculations, in particular
in the forward (proton) direction. The large data sample also allows the study
of dijet production associated with charm. A significant resolved as well as a
direct photon component contribute to the cross section. Leading order QCD
Monte Carlo calculations indicate that the resolved contribution arises from a
significant charm component in the photon. A massive charm NLO parton level
calculation yields lower cross sections compared to the measured results in a
kinematic region where the resolved photon contribution is significant.Comment: 32 pages including 6 figure
Measurement of Jet Shapes in Photoproduction at HERA
The shape of jets produced in quasi-real photon-proton collisions at
centre-of-mass energies in the range GeV has been measured using the
hadronic energy flow. The measurement was done with the ZEUS detector at HERA.
Jets are identified using a cone algorithm in the plane with a
cone radius of one unit. Measured jet shapes both in inclusive jet and dijet
production with transverse energies GeV are presented. The jet
shape broadens as the jet pseudorapidity () increases and narrows
as increases. In dijet photoproduction, the jet shapes have been
measured separately for samples dominated by resolved and by direct processes.
Leading-logarithm parton-shower Monte Carlo calculations of resolved and direct
processes describe well the measured jet shapes except for the inclusive
production of jets with high and low . The observed
broadening of the jet shape as increases is consistent with the
predicted increase in the fraction of final state gluon jets.Comment: 29 pages including 9 figure
Taxonomy of the order Bunyavirales : second update 2018
In October 2018, the order Bunyavirales was amended by inclusion of the family Arenaviridae, abolishment of three families, creation of three new families, 19 new genera, and 14 new species, and renaming of three genera and 22 species. This article presents the updated taxonomy of the order Bunyavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV).Non peer reviewe
Measurement of the Diffractive Cross Section in Deep Inelastic Scattering using ZEUS 1994 Data
The DIS diffractive cross section, , has been measured in the mass range GeV for c.m. energies GeV and photon virtualities to 140 GeV. For fixed and , the diffractive cross section rises rapidly with , with corresponding to a -averaged pomeron trajectory of \bar{\alphapom} = 1.127 \pm 0.009 (stat)^{+0.039}_{-0.012} (syst) which is larger than \bar{\alphapom} observed in hadron-hadron scattering. The dependence of the diffractive cross section is found to be the same as that of the total cross section for scattering of virtual photons on protons. The data are consistent with the assumption that the diffractive structure function factorizes according to \xpom F^{D(3)}_2 (\xpom,\beta,Q^2) = (x_0/ \xpom)^n F^{D(2)}_2(\beta,Q^2). They are also consistent with QCD based models which incorporate factorization breaking. The rise of \xpom F^{D(3)}_2 with decreasing \xpom and the weak dependence of on suggest a substantial contribution from partonic interactions
Measurement of the F2 structure function in deep inelastic ep scattering using 1994 data from the ZEUS detector at HERA
We present measurements of the structure function \Ft\ in e^+p scattering at HERA in the range 3.5\;\Gevsq < \qsd < 5000\;\Gevsq. A new reconstruction method has allowed a significant improvement in the resolution of the kinematic variables and an extension of the kinematic region covered by the experiment. At \qsd < 35 \;\Gevsq the range in x now spans 6.3\cdot 10^{-5} < x < 0.08 providing overlap with measurements from fixed target experiments. At values of Q^2 above 1000 GeV^2 the x range extends to 0.5. Systematic errors below 5\perc\ have been achieved for most of the kinematic urray, W
Taxonomy of the family Arenaviridae and the order Bunyavirales : update 2018
In 2018, the family Arenaviridae was expanded by inclusion of 1 new genus and 5 novel species. At the same time, the recently established order Bunyavirales was expanded by 3 species. This article presents the updated taxonomy of the family Arenaviridae and the order Bunyavirales as now accepted by the International Committee on Taxonomy of Viruses (ICTV) and summarizes additional taxonomic proposals that may affect the order in the near future.Peer reviewe
Exclusive Electroproduction of and Mesons at HERA
Exclusive production of and mesons in e^+ p collisions has
been studied with the ZEUS detector in the kinematic range for the data and for the data. Cross sections for exclusive and
production have been measured as a function of and . The
spin-density matrix elements and have
been determined for exclusive production as well as and
for exclusive production.
The results are discussed in the context of theoretical models invoking soft
and hard phenomena.Comment: 57 pages including 21 figures, minor modifications to Figs. 19-21,
these figures supercede those of Eur. Phys. J. C6 (1999) 603-62
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