2,697 research outputs found
HEP Applications Evaluation of the EDG Testbed and Middleware
Workpackage 8 of the European Datagrid project was formed in January 2001
with representatives from the four LHC experiments, and with experiment
independent people from five of the six main EDG partners. In September 2002
WP8 was strengthened by the addition of effort from BaBar and D0. The original
mandate of WP8 was, following the definition of short- and long-term
requirements, to port experiment software to the EDG middleware and testbed
environment. A major additional activity has been testing the basic
functionality and performance of this environment. This paper reviews
experiences and evaluations in the areas of job submission, data management,
mass storage handling, information systems and monitoring. It also comments on
the problems of remote debugging, the portability of code, and scaling problems
with increasing numbers of jobs, sites and nodes. Reference is made to the
pioneeering work of Atlas and CMS in integrating the use of the EDG Testbed
into their data challenges. A forward look is made to essential software
developments within EDG and to the necessary cooperation between EDG and LCG
for the LCG prototype due in mid 2003.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
Conference (CHEP03), La Jolla, CA, USA, March 2003, 7 pages. PSN THCT00
Interference Study of the chi_c0 (1^3P_0) in the Reaction Proton-Antiproton -> pi^0 pi^0
Fermilab experiment E835 has observed proton-antiproton annihilation
production of the charmonium state chi_c0 and its subsequent decay into pi^0
pi^0. Although the resonant amplitude is an order of magnitude smaller than
that of the non-resonant continuum production of pi^0 pi^0, an enhanced
interference signal is evident. A partial wave expansion is used to extract
physics parameters. The amplitudes J=0 and 2, of comparable strength, dominate
the expansion. Both are accessed by L=1 in the entrance proton-antiproton
channel. The product of the input and output branching fractions is determined
to be B(pbar p -> chi_c0) x B(chi_c0 -> pi^0 pi^0)= (5.09 +- 0.81 +- 0.25) x
10^-7.Comment: 4 pages, 4 figures, Accepted by PRL (July 2003
Universal behavior in the scattering of heavy, weakly interacting dark matter on nuclear targets
Particles that are heavy compared to the electroweak scale (), and
that are charged under electroweak SU(2) gauge interactions display universal
properties such as a characteristic fine structure in the mass spectrum induced
by electroweak symmetry breaking, and an approximately universal cross section
for scattering on nuclear targets. The heavy particle effective theory
framework is developed to compute these properties. As illustration, the spin
independent cross section for low-velocity scattering on a nucleon is evaluated
in the limit , including complete leading-order matching onto quark
and gluon operators, renormalization analysis, and systematic treatment of
perturbative and hadronic-input uncertainties.Comment: 17 pages, 2 figures. v2: minor changes, version to appear in Phys.
Lett.
Skyrmion Multi-Walls
Skyrmion walls are topologically-nontrivial solutions of the Skyrme system
which are periodic in two spatial directions. We report numerical
investigations which show that solutions representing parallel multi-walls
exist. The most stable configuration is that of the square -wall, which in
the limit becomes the cubically-symmetric Skyrme crystal. There is
also a solution resembling parallel hexagonal walls, but this is less stable.Comment: 7 pages, 1 figur
Subcritical Fluctuations at the Electroweak Phase Transition
We study the importance of thermal fluctuations during the electroweak phase
transition. We evaluate in detail the equilibrium number density of large
amplitude subcritical fluctuations and discuss the importance of phase mixing
to the dynamics of the phase transition. Our results show that, for realistic
Higgs masses, the phase transition can be completed by the percolation of the
true vacuum, induced by the presence of subcritical fluctuations.Comment: RevTeX, 4 eps figs (uses epsf.sty), 26 pages, to be published in
Phys. Rev.
Gamma Lines without a Continuum: Thermal Models for the Fermi-LAT 130 GeV Gamma Line
Recent claims of a line in the Fermi-LAT photon spectrum at 130 GeV are
suggestive of dark matter annihilation in the galactic center and other dark
matter-dominated regions. If the Fermi feature is indeed due to dark matter
annihilation, the best-fit line cross-section, together with the lack of any
corresponding excess in continuum photons, poses an interesting puzzle for
models of thermal dark matter: the line cross-section is too large to be
generated radiatively from open Standard Model annihilation modes, and too
small to provide efficient dark matter annihilation in the early universe. We
discuss two mechanisms to solve this puzzle and illustrate each with a simple
reference model in which the dominant dark matter annihilation channel is
photonic final states. The first mechanism we employ is resonant annihilation,
which enhances the annihilation cross-section during freezeout and allows for a
sufficiently large present-day annihilation cross section. Second, we consider
cascade annihilation, with a hierarchy between p-wave and s-wave processes.
Both mechanisms require mass near-degeneracies and predict states with masses
closely related to the dark matter mass; resonant freezeout in addition
requires new charged particles at the TeV scale.Comment: 17 pages, 8 figure
A new approach for almost automatic installation of elastic cloud infrastructures
In the context of the cloud infrastructures at the INFN computing center of Torino, we implemented new simplified tools based up on OpenNebula cloud manager for almost automatic deployment of standard cloud infrastructure,
monitoring, maintenance, and VMs management within elastic cloud infrastructures. Such new tools for small and medium infrastructures could significantly improve their usability and efficiency by simplifying the installation and set up processes, providing easier access to elastic cloud technologies to sites with limited specific knowledge or dedicated manpower; introducing flexibility in a dynamic allocation of resources to the different stakeholders in one single infrastructure, maximizing the efficiency
Magnetic Fluffy Dark Matter
We explore extensions of inelastic Dark Matter and Magnetic inelastic Dark
Matter where the WIMP can scatter to a tower of heavier states. We assume a
WIMP mass GeV and a constant splitting between
successive states keV. For the
spin-independent scattering scenario we find that the direct experiments CDMS
and XENON strongly constrain most of the DAMA/LIBRA preferred parameter space,
while for WIMPs that interact with nuclei via their magnetic moment a region of
parameter space corresponding to GeV and keV
is allowed by all the present direct detection constraints.Comment: 16 pages, 6 figures, added comments about magnetic moment form factor
to Sec 3.1.2 and results to Sec 3.2.2, final version to be published in JHE
E835 at FNAL: Charmonium Spectroscopy in Annihilations
I present preliminary results on the search for in its
and decay modes. We observe an excess of \eta_c\gamma{\cal P} \sim 0.001M=3525.8 \pm 0.2 \pm 0.2
\Gamma\leq10.6\pm 3.7\pm3.4(br) <
\Gamma_{\bar{p}p}B_{\eta_c\gamma} < 12.8\pm 4.8\pm4.5(br) J/\psi\pi^0$ mode.Comment: Presented at the 6th International Conference on Hyperons, Charm and
Beauty Hadrons (BEACH 2004), Chicago(Il), June 27-July 3,200
Precision measurements of the total and partial widths of the psi(2S) charmonium meson with a new complementary-scan technique in antiproton-proton annihilations
We present new precision measurements of the psi(2S) total and partial widths
from excitation curves obtained in antiproton-proton annihilations by Fermilab
experiment E835 at the Antiproton Accumulator in the year 2000. A new technique
of complementary scans was developed to study narrow resonances with
stochastically cooled antiproton beams. The technique relies on precise
revolution-frequency and orbit-length measurements, while making the analysis
of the excitation curve almost independent of machine lattice parameters. We
study the psi(2S) meson through the processes pbar p -> e+ e- and pbar p ->
J/psi + X -> e+ e- + X. We measure the width to be Gamma = 290 +- 25(sta) +-
4(sys) keV and the combination of partial widths Gamma_e+e- * Gamma_pbarp /
Gamma = 579 +- 38(sta) +- 36(sys) meV, which represent the most precise
measurements to date.Comment: 17 pages, 3 figures, 3 tables. Final manuscript accepted for
publication in Phys. Lett. B. Parts of the text slightly expanded or
rearranged; results are unchange
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