1,450 research outputs found
Neutrinos: the Key to UHE Cosmic Rays
Observations of ultrahigh energy cosmic rays (UHECR) do not uniquely
determine both the injection spectrum and the evolution model for UHECR sources
- primarily because interactions during propagation obscure the early Universe
from direct observation. Detection of neutrinos produced in those same
interactions, coupled with UHECR results, would provide a full description of
UHECR source properties.Comment: three pages, three figures. corrected typo
Tracing the general structure of Galactic molecular clouds using Planck data: I. The Perseus region as a test case
We present an analysis of probability distribution functions (pdfs) of column
density in different zones of the star-forming region Perseus and its diffuse
environment based on the map of dust opacity at 353 GHz available from the
Planck archive. The pdf shape can be fitted by a combination of a lognormal
function and an extended power-law tail at high densities, in zones centred at
the molecular cloud Perseus. A linear combination of several lognormals fits
very well the pdf in rings surrounding the cloud or in zones of its diffuse
neighbourhood. The slope of the mean density scaling law is steep () in the former case and rather
shallow () in the rings delineated around the cloud. We
interpret these findings as signatures of two distinct physical regimes: i) a
gravoturbulent one which is characterized by nearly linear scaling of mass and
practical lack of velocity scaling; and ii) a predominantly turbulent one which
is best described by steep velocity scaling and by invariant for compressible
turbulence , describing a scale-independent flux
of the kinetic energy per unit volume through turbulent cascade. The
gravoturbulent spatial domain can be identified with the molecular cloud
Perseus while a relatively sharp transition to predominantly turbulent regime
occurs in its vicinity.Comment: Accepted for publication in MNRAS; 16 pages with Appendix, 15 figure
The 3d-to-4s-by-2p highway to superconductivity in cuprates
High-temperature superconductors are nowadays found in great variety and hold
technological promise. It is still an unsolved mystery that the critical
temperature T_c of the basic cuprates is so high. The answer might well be
hidden in a conventional corner of theoretical physics, overlooked in the
recent hunt for exotic explanations of new effects in these materials. A
forgotten intra-atomic s-d two-electron exchange in the Cu atom is found to
provide a strong (~eV) electron pairing interaction. A
Bardeen-Cooper-Schrieffer approach can explain the main experimental
observations and predict the correct d_{x^2-y^2} symmetry of the gap.Comment: 4 pages, 3 figures, LaTeX2
High Energy Neutrinos from Cosmic Ray Interactions in Clusters of Galaxies
The spatial clustering of galaxies in galaxy clusters implies that the
background of infrared (IR) light in the intracluster medium (ICM) may exceed
the universal background. Cosmic rays injected within the ICM propagate
diffusively and at low enough energies are trapped there for cosmological
times. The photopion production interactions of cosmic rays with the IR photons
are responsible for the generation of neutrinos whose detection may shed some
light on the origin and propagation of high energy cosmic rays in the universe.
Here we discuss our calculations of the flux of neutrinos from single clusters
as well as the contribution of photopion production in clusters of galaxies to
the diffuse neutrino background.Comment: 10 pages, 10 figures, submitted to PR
High Energy Neutrinos: Sources and Fluxes
We discuss briefly the potential sources of high energy astrophysical
neutrinos and show estimates of the neutrino fluxes that they can produce. A
special attention is paid to the connection between the highest energy cosmic
rays and astrophysical neutrinos.Comment: 7 pages, 2 figures, submitted to the Proceedings of TAUP 2005
workshop, corrected left panel of figure
Predicting Proton-Air Cross Sections at sqrt s ~30 TeV, using Accelerator and Cosmic Ray Data
We use the high energy predictions of a QCD-inspired parameterization of all
accelerator data on forward proton-proton and antiproton-proton scattering
amplitudes, along with Glauber theory, to predict proton-air cross sections at
energies near \sqrt s \approx 30 TeV. The parameterization of the proton-proton
cross section incorporates analyticity and unitarity, and demands that the
asymptotic proton is a black disk of soft partons. By comparing with the p-air
cosmic ray measurements, our analysis results in a constraint on the inclusive
particle production cross section.Comment: 9 pages, Revtex, uses epsfig.sty, 5 postscript figures. Minor text
revisions. Systematic errors in k included, procedure for extracting k
clarified. Previously undefined symbols now define
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