361 research outputs found
Theoretical study of the dynamic structure factor of superfluid 4He
We study the dynamic structure factor of superfluid 4He
at zero temperature in the roton momentum region and beyond using
field-theoretical Green's function techniques. We start from the
Gavoret-Nozi\`{e}res two-particle propagator and introduce the concept of
quasiparticles. We treat the residual (weak) interaction between quasiparticles
as being local in coordinate space and weakly energy dependent. Our
quasiparticle model explicitly incorporates the Bose-Einstein condensate. A
complete formula for the dynamic susceptibility, which is related to , is derived. The structure factor is numerically calculated
in a self-consistent way in the special case of a momentum independent
interaction between quasiparticles. Results are compared with experiment and
other theoretical approaches.Comment: 17 pages, 16 figure
Radiative decays of decuplet hyperons
We calculate the radiative decay widths of decuplet hyperons in a chiral
constituent quark model including electromagnetic exchange currents between
quarks. Exchange currents contribute significantly to the E2 transition
amplitude, while they largely cancel for the M1 transition amplitude.
Strangeness suppression of the radiative hyperon decays is found to be weakened
by exchange currents. Differences and similarities between our results and
other recent model predictions are discussed.Comment: 11 pages, 1 eps figure, revtex, accepted for publication in Phys.
Rev.
Muscle-specific ablation of glucose transporter 1 (GLUT1) does not impair basal or overload-stimulated skeletal muscle glucose uptake
Glucose transporter 1 (GLUT1) is believed to solely mediate basal (insulin-independent) glucose uptake in skeletal muscle; yet recent work has demonstrated that mechanical overload, a model of resistance exercise training, increases muscle GLUT1 levels. The primary objective of this study was to determine if GLUT1 is necessary for basal or overload-stimulated muscle glucose uptake. Muscle-specific GLUT1 knockout (mGLUT1KO) mice were generated and examined for changes in body weight, body composition, metabolism, systemic glucose regulation, muscle glucose transporters, and muscle
Comment on “Unique Translation between Hamiltonian Operators and Functional Integrals”
A comment on the letter by Tim Gollisch and Christof Wetterich, Phys. Rev. Lett. 86, 1 (2001).Michael Weyrauch, and Andreas W. Schreibe
Non-perturbative Gluons and Pseudoscalar Mesons in Baryon Spectroscopy
We study baryon spectroscopy including the effects of pseudoscalar meson
exchange and one gluon exchange potentials between quarks, governed by
. The non-perturbative, hyperspherical method calculations show that
one can obtain a good description of the data by using a quark-meson coupling
constant that is compatible with the measured pion-nucleon coupling constant,
and a reasonably small value of .Comment: 12 pages; Submitted to Phys. Rev. C. Rapid Communication
Measurement of atmospheric neutrino mixing with improved IceCube DeepCore calibration and data processing
We describe a new data sample of IceCube DeepCore and report on the latest measurement of atmospheric neutrino oscillations obtained with data recorded between 2011–2019. The sample includes significant improvements in data calibration, detector simulation, and data processing, and the analysis benefits from a sophisticated treatment of systematic uncertainties, with significantly greater level of detail since our last study. By measuring the relative fluxes of neutrino flavors as a function of their reconstructed energies and arrival directions we constrain the atmospheric neutrino mixing parameters to be sin2θ23=0.51±0.05 and Δm232=2.41±0.07×10−3 eV2, assuming a normal mass ordering. The errors include both statistical and systematic uncertainties. The resulting 40% reduction in the error of both parameters with respect to our previous result makes this the most precise measurement of oscillation parameters using atmospheric neutrinos. Our results are also compatible and complementary to those obtained using neutrino beams from accelerators, which are obtained at lower neutrino energies and are subject to different sources of uncertainties
Search for Extended Sources of Neutrino Emission in the Galactic Plane with IceCube
The Galactic plane, harboring a diffuse neutrino flux, is a particularly
interesting target to study potential cosmic-ray acceleration sites. Recent
gamma-ray observations by HAWC and LHAASO have presented evidence for multiple
Galactic sources that exhibit a spatially extended morphology and have energy
spectra continuing beyond 100 TeV. A fraction of such emission could be
produced by interactions of accelerated hadronic cosmic rays, resulting in an
excess of high-energy neutrinos clustered near these regions. Using 10 years of
IceCube data comprising track-like events that originate from charged-current
muon neutrino interactions, we perform a dedicated search for extended neutrino
sources in the Galaxy. We find no evidence for time-integrated neutrino
emission from the potential extended sources studied in the Galactic plane. The
most significant location, at 2.6 post-trials, is a 1.7 sized
region coincident with the unidentified TeV gamma-ray source 3HWC J1951+266. We
provide strong constraints on hadronic emission from several regions in the
Galaxy.Comment: 13 pages, 4 figures, 5 tables including an appendix. Accepted for
publication in Astrophysical Journa
Measurement of Atmospheric Neutrino Mixing with Improved IceCube DeepCore Calibration and Data Processing
We describe a new data sample of IceCube DeepCore and report on the latest
measurement of atmospheric neutrino oscillations obtained with data recorded
between 2011-2019. The sample includes significant improvements in data
calibration, detector simulation, and data processing, and the analysis
benefits from a detailed treatment of systematic uncertainties, with
significantly higher level of detail since our last study. By measuring the
relative fluxes of neutrino flavors as a function of their reconstructed
energies and arrival directions we constrain the atmospheric neutrino mixing
parameters to be and , assuming a normal mass ordering. The
resulting 40\% reduction in the error of both parameters with respect to our
previous result makes this the most precise measurement of oscillation
parameters using atmospheric neutrinos. Our results are also compatible and
complementary to those obtained using neutrino beams from accelerators, which
are obtained at lower neutrino energies and are subject to different sources of
uncertainties
Limits on Neutrino Emission from GRB 221009A from MeV to PeV using the IceCube Neutrino Observatory
Gamma-ray bursts (GRBs) have long been considered a possible source of
high-energy neutrinos. While no correlations have yet been detected between
high-energy neutrinos and GRBs, the recent observation of GRB 221009A - the
brightest GRB observed by Fermi-GBM to date and the first one to be observed
above an energy of 10 TeV - provides a unique opportunity to test for hadronic
emission. In this paper, we leverage the wide energy range of the IceCube
Neutrino Observatory to search for neutrinos from GRB 221009A. We find no
significant deviation from background expectation across event samples ranging
from MeV to PeV energies, placing stringent upper limits on the neutrino
emission from this source.Comment: Version in ApJ Letters Focus on the Ultra-luminous Gamma-Ray Burst
GRB 221009
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