73,844 research outputs found
Reconclining phi radiative decays with other data for a0(980), fo(980), pi-pi -> KK and pi-pi -> eta-eta
Data for phi -> gamma (eta-pizero) are analysed using the KK loop model and
compared with parameters of a0(980) derived from Crystal Barrel data. The
eta-pi mass spectrum agrees closely and the absolute normalisation lies just
within errors. However, BES parameters for fo(980) predict a normalisation for
phi -> gamma (pizero-pizero) at least a factor 2 lower than is observed. This
discrepancy may be eliminated by including constructive interference between
fo(980) and sigma. The magnitude required for sigma -> KK is consistent with
data on pi-pi -> KK. A dispersion relation analysis by Buttiker, Descotes-Genon
and Moussallam of pi-pi -> KK leads to a similar conclusion. Data on pi-pi ->
eta-eta also require decays of sigma to eta-eta. Four sets of pi-pi -> KK data
all require a small but definite fo(1370) signal.Comment: 21 pages, 11 figures, Small rearrangement of reference
Updated galactic radio constraints on Dark Matter
We perform a detailed analysis of the synchrotron signals produced by Dark
Matter annihilations and decays. We consider different set-ups for the
propagation of electrons and positrons, the galactic magnetic field and Dark
Matter properties. We then confront these signals with radio and microwave
maps, including Planck measurements, from a frequency of 22 MHz up to 70 GHz.
We derive two sets of constraints: conservative and progressive, the latter
based on a modeling of the astrophysical emission. Radio and microwave
constraints are complementary to those obtained with other indirect detection
methods, especially for dark matter annihilating into leptonic channels.Comment: 20 pages, 10 figures. v2: some small additions, matches journal
versio
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
Learning Bayesian Networks with the bnlearn R Package
bnlearn is an R package which includes several algorithms for learning the
structure of Bayesian networks with either discrete or continuous variables.
Both constraint-based and score-based algorithms are implemented, and can use
the functionality provided by the snow package to improve their performance via
parallel computing. Several network scores and conditional independence
algorithms are available for both the learning algorithms and independent use.
Advanced plotting options are provided by the Rgraphviz package.Comment: 22 pages, 4 picture
Soliton dynamics for fractional Schrodinger equations
We investigate the soliton dynamics for the fractional nonlinear Schrodinger
equation by a suitable modulational inequality. In the semiclassical limit, the
solution concentrates along a trajectory determined by a Newtonian equation
depending of the fractional diffusion parameter.Comment: 22 page
Ground states for fractional magnetic operators
We study a class of minimization problems for a nonlocal operator involving
an external magnetic potential. The notions are physically justified and
consistent with the case of absence of magnetic fields. Existence of solutions
is obtained via concentration compactness.Comment: 22 pages, minor corrections and typos fixe
Crack propagation in honeycomb cellular materials: a computational approach
Computational models based on the finite element method and linear or nonlinear fracture mechanics are herein proposed to study the mechanical response of functionally designed cellular components. It is demonstrated that, via a suitable tailoring of the properties of interfaces present in the meso- and micro-structures, the tensile strength can be substantially increased as compared to that of a standard polycrystalline material. Moreover, numerical examples regarding the structural response of these components when subjected to loading conditions typical of cutting operations are provided. As a general trend, the occurrence of tortuous crack paths is highly favorable: stable crack propagation can be achieved in case of critical crack growth, whereas an increased fatigue life can be obtained for a sub-critical crack propagation
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