794 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
Neutrino Cross Sections: Interface of shallow- and deep-inelastic scattering for collider neutrinos
Neutrino experiments in a Forward Physics Facility at the Large Hadron
Collider can measure neutrino and antineutrino cross sections for energies up
to a few TeV. For neutrino energies below 100 GeV, the inelastic cross section
evaluations have contributions from weak structure functions at low momentum
transfers and low hadronic final state invariant mass. To evaluate the size of
these contributions to the neutrino cross section, we use a parametrization of
the electron-proton structure function, adapted for neutrino scattering,
augmented with a correction to account for the partial conservation of the
axial vector current, and normalized to structure functions evaluated at
next-to-leading order in QCD, with target mass corrections and heavy quark
corrections. We compare our results with other approaches to account for this
kinematic region in neutrino cross section for energies between 10--1000 GeV on
isoscalar nucleon and iron targets.Comment: 16 pages, 10 figure
Color dipole cross section and inelastic structure function
Instead of starting from a theoretically motivated form of the color dipole
cross section in the dipole picture of deep inelastic scattering, we start with
a parametrization of the deep inelastic structure function for electromagnetic
scattering with protons, and then extract the color dipole cross section. Using
the parametrizations of by Donnachie-Landshoff
and Block et al., we find the dipole cross section from an approximate form of
the presumed dipole cross section convoluted with the perturbative photon wave
function for virtual photon splitting into a color dipole with massless quarks.
The color dipole cross section determined this way reproduces the original
structure function within about 10\% for GeV GeV.
We discuss the large and small form of the dipole cross section and compare
with other parameterizations.Comment: 11 pages, 12 figure
Forward production of prompt neutrinos from charm in the atmosphere and at high energy colliders
The high-energy atmospheric neutrino flux is dominated by neutrinos from the
decays of charmed hadrons produced in the forward direction by cosmic ray
interactions with air nuclei. We evaluate the charm contributions to the prompt
atmospheric neutrino flux as a function of the center-of-mass energy
of the hadronic collision and of the center-of-mass rapidity of the
produced charm hadron. Uncertainties associated with parton distribution
functions are also evaluated as a function of . We find that the
coverage of LHCb for forward heavy-flavour production, complemented by the
angular coverage of present and future forward neutrino experiments at the LHC,
bracket the most interesting regions for the prompt atmospheric neutrino
flux. At TeV foreseen for the HL-LHC phase, nucleon collisions in
air contribute to the prompt neutrino flux prominently below ~GeV. Measurements of forward charm and/or forward neutrinos produced in
hadron collisions up to TeV, which might become possible at the
FCC, are relevant for the prompt atmospheric neutrino flux up to
GeV and beyond.Comment: 29 pages, 11 figure
Radio Cherenkov signals from the Moon: neutrinos and cosmic rays
Neutrino production of radio Cherenkov signals in the Moon is the object of
radio telescope observations. Depending on the energy range and detection
parameters, the dominant contribution to the neutrino signal may come from
interactions of the neutrino on the Moon facing the telescope, rather than
neutrinos that have traversed a portion of the Moon. Using the approximate
analytic expression of the effective lunar aperture from a recent paper by
Gayley, Mutel and Jaeger, we evaluate the background from cosmic ray
interactions in the lunar regolith. We also consider the modifications to the
effective lunar aperture from generic non-standard model neutrino interactions.
A background to neutrino signals are radio Cherenkov signals from cosmic ray
interactions. For cosmogenic neutrino fluxes, neutrino signals will be
difficult to observe because of low neutrino flux at the high energy end and
large cosmic ray background in the lower energy range considered here. We show
that lunar radio detection of neutrino interactions is best suited to constrain
or measure neutrinos from astrophysical sources and probe non-standard
neutrino-nucleon interactions such as microscopic black hole production.Comment: 16 pages, 19 figure
Association between diet and gallstones of cholesterol and pigment among patients with cholecystectomy: a case-control study in Korea
Background: The prevalence of cholesterol gallstones is high in Western
populations, while pigment gallstones are common in Asian populations.
Dietary factors are suggested to be associated with gallstone risk, but
their relationship with gallstone type has not been evaluated. This
study investigated the association between diet and risk of cholesterol
gallstone or pigment gallstone in a Korean population whose dietary
pattern and type of gallstone were changed during the last 30 years.
Methods: Patients with cholesterol (n = 40) and pigment (n = 59)
gallstones were recruited after laparoscopic cholecystectomy and were
compared with those of age- and sex-matched controls without gallstones
(n = 99). Dietary intakes were assessed by trained dietitians using a
semi-quantitative food frequency questionnaire. Multinomial logistic
regression analysis was performed to calculate odds ratios and 95%
confidence intervals to examine the associations between diet and risk
for type of gallstones adjusted by potential confounders. Results:
Patients with cholesterol gallstone consumed more lipid, animal lipid,
beef, pork, and fried food than those with pigment gallstones and
control, while patients with pigment gallstone consumed more
carbohydrate and noodles than patients with cholesterol gallstone and
control. In multinomial logistic regression analysis using control as
reference group, dietary pattern with high consumption of beef, pork,
and fried food was associated with risk of cholesterol gallstones,
while there was no association between the risk of pigment gallstone
and dietary pattern. In addition, control consumed more alcohol than
patients with cholesterol and pigment gallstones. Conclusions: The
present study suggested consumption of fat from meat and fried foods
increased the risk of cholesterol gallstone, and intake of carbohydrate
from noodles increased the risk of pigment gallstone
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