4,265 research outputs found
Extraction of the atmospheric neutrino fluxes from experimental event rate data
The precise knowledge of the atmospheric neutrino fluxes is a key ingredient
in the interpretation of the results from any atmospheric neutrino experiment.
In the standard atmospheric neutrino data analysis, these fluxes are
theoretical inputs obtained from sophisticated numerical calculations. In this
contribution we present an alternative approach to the determination of the
atmospheric neutrino fluxes based on the direct extraction from the
experimental data on neutrino event rates. The extraction is achieved by means
of a combination of artificial neural networks as interpolants and Monte Carlo
methods.Comment: 6 pages, 2 figs, to appear in the proceedings of the 2nd
International Conference on Quantum Theories and Renormalization Group in
Gravity and Cosmology, Barcelona, July 200
Coulomb Drag between One-Dimensional Wigner Crystal Rings
We consider the Coulomb drag between two metal rings in which the long range
Coulomb interaction leads to the formation of a Wigner crystal. The first ring
is threaded by an Ahranov Bohm flux creating a persistent current J_0. The
second ring is brought in close proximity to the second and due to the Coulomb
interaction between the two rings a drag current J_D is produced in the second.
We investigate this system at zero temperature for perfect rings as well as the
effects of impurities. We show that the Wigner crystal state can in principle
lead to a higher ratio of drag current to drive current J_D/J_0 than in weakly
interacting electron systems.Comment: 12 pages, 10 figure
Theory and experiment of the ESR of Co in Zn % (OH)PO and Mg(OH)AsO
Experiments of Electron Spin Resonance (ESR) were performed on Co
substituting Zn or Mg in powder samples of Zn(OH)PO and
Mg(OH)AsO. The observed resonances are described with a theoretical
model that considers the departures from the two perfect structures. It is
shown that the resonance in the penta-coordinated complex is allowed, and the
crystal fields that would describe the resonance of the Co in the two
environments are calculated. The small intensity of the resonance in the
penta-coordinated complex is explained assuming that this site is much less
populated than the octahedral one; this assumption was verified by a molecular
calculation of the energies of the two environments, with both Co and Zn as
central ions in Zn(OH)PO.Comment: 43 pages, LaTex file, 6 figures, EPS. submitted to Journal of Physics
Condens
A decreasing sequence of eigenvalue localization regions
AbstractWe construct a decreasing sequence of rectangles (Rp) in such a way that all the eigenvalues of a complex matrix A are contained in each rectangle. When A is a matrix with real spectrum or a normal matrix, each Rp can be obtained without knowing the eigenvalues of A
Constraints on hidden gravitons from fifth-force experiments and stellar energy loss
We study different phenomenological signatures associated with new spin-2
particles. These new degrees of freedom, that we call hidden gravitons, arise
in different high-energy theories such as extra-dimensional models or
extensions of General Relativity. At low energies, hidden gravitons can be
generally described by the Fierz-Pauli Lagrangian. Their phenomenology is
parameterized by two dimensionful constants: their mass and their coupling
strength. In this work, we analyze two different sets of constraints. On the
one hand, we study potential deviations from the inverse-square law on
solar-system and laboratory scales. To extend the constraints to scales where
the laboratory probes are not competitive, we also study consequences on
astrophysical objects. We analyze in detail the processes that may take place
in stellar interiors and lead to emission of hidden gravitons, acting like an
additional source of energy loss.Comment: 15 pages, 7 figure
Family Businesses, Choices of Legal Entity
There is not a âbestâ choice of legal entity for Family Business in the USA and in Argentina. The different legal choices provide with âbetterâ or âworseâ options of legal entity according with the entrepreneursâ expectations and concerns. However, some legislation in the USA has recognized the special characteristics of Family Businesses, and allows more possibilities of customization of the governance structure and succession planning of such businesses. Argentinaâs law should follow that pat
Mass and density of B-type asteroid (702) Alauda
Observations with the adaptive optics system on the Very Large Telescope
reveal that outer main belt asteroid (702) Alauda has a small satellite with
primary to secondary diameter ratio of 56. The secondary revolves around
the primary in 4.9143 0.007 days at a distance of 1227 24 km,
yielding a total system mass of (6.057 0.36) 10 kg.
Combined with an IRAS size measurement, our data yield a bulk density for this
B-type asteroid of 1570 500 kg~m.Comment: In press, ApJ 2011. 6 pages, 4 figure
Neural network determination of the non-singlet quark distribution
We summarize the main features of our approach to parton fitting, and we show
a preliminary result for the non-singlet structure function. When comparing our
result to other PDF sets, we find a better description of large x data and
larger error bands in the extrapolation regions.Comment: 4 pages, 1 eps figure. Presented at the XIV International Workshop on
Deep Inelastic Scattering (DIS2006), Tsukuba, Japan, 20-24 April 200
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