904 research outputs found
Quark mass effects in high energy neutrino nucleon scattering
We evaluate the neutrino nucleon charged current cross section at
next-to-leading order in quantum chromodynamic corrections in the variable
flavor number scheme and the fixed flavor number scheme, taking into account
quark masses. The number scheme dependence is largest at the highest energies
considered here, GeV, where the cross sections differ by
approximately 15 percent. We illustrate the numerical implications of the
inconsistent application of the fixed flavor number scheme.Comment: 8 pages, 8 figures, v2: updated pdfs, version accepted for
publicatio
Target Mass Corrections to Electro-Weak Structure Functions and Perturbative Neutrino Cross Sections
We provide a complete and consistent framework to include subasymptotic
perturbative as well as mass corrections to the leading twist (tau=2)
evaluation of charged and neutral current weak structure functions and the
perturbative neutrino cross sections. We revisit previous calculations in a
modern language and fill in the gaps that we find missing for a complete and
ready-to-use "NLO xi-scaling" formulary. In particular, as a new result we
formulate the mixing of the partonic and hadronic structure function tensor
basis in the operator approach to deep inelastic scattering. As an underlying
framework we follow the operator product expansion a la Georgi & Politzer that
allows the inclusion of target mass corrections at arbitrary order in QCD and
we provide explicit analytical and numerical results at NLO. We compare this
approach with a simpler collinear parton model approach to xi-scaling. Along
with target mass corrections we include heavy quark mass effects as a
calculable leading twist power suppressed correction. The complete corrections
have been implemented into a Monte Carlo integration program to evaluate
structure functions and/or integrated cross sections. As applications, we
compare the operator approach with the collinear approximation numerically and
we investigate the NLO and mass corrections to observables that are related to
the extraction of the weak mixing angle from a Paschos-Wolfenstein-like
relation in neutrino-iron scattering. We expect that the interpretation of
neutrino scattering events in terms of oscillation physics and electroweak
precision physics will benefit from our results.Comment: 26 pages, 5 figures, note added, to appear in PR
Clinical evaluation of the Cepheid Xpert TV assay for detection of Trichomonas vaginalis with prospectively collected specimens from men and women
Ultrahigh Energy Tau Neutrinos
We study ultrahigh energy astrophysical neutrinos and the contribution of tau
neutrinos from neutrino oscillations, relative to the contribution of the other
flavors. We show the effect of tau neutrino regeneration and tau energy loss as
they propagate through the Earth. We consider a variety of neutrino fluxes,
such as cosmogenic neutrinos and neutrinos that originate in Active Galactic
Nuclei. We discuss signals of tau neutrinos in detectors such as IceCube, RICE
and ANITA.Comment: Invited talk given at the ``8th Workshop on Non-Perturbative Quantum
Chromodynamics", June 7-11, 2004, Paris, France; 10 pages, 6 figure
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