3,933 research outputs found
Slepton pair production in the POWHEG BOX
We present an implementation for slepton pair production at hadron colliders
in the POWHEG BOX, a framework for combining next-to-leading order QCD
calculations with parton-shower Monte-Carlo programs. Our code provides a SUSY
Les Houches Accord interface for setting the supersymmetric input parameters.
Decays of the sleptons and parton-shower effects are simulated with PYTHIA.
Focussing on a representative point in the supersymmetric parameter space we
show results for kinematic distributions that can be observed experimentally.
While next-to-leading order QCD corrections are sizable for all distributions,
the parton shower affects the color-neutral particles only marginally.
Pronounced parton-shower effects are found for jet distributions.Comment: 10 pages, 4 figure
Anisotropic Colossal Magnetoresistance Effects in Fe_{1-x}Cu_xCr_2S_4
A detailed study of the electronic transport and magnetic properties of
FeCuCrS () on single crystals is presented. The
resistivity is investigated for K in magnetic fields up to
14 Tesla and under hydrostatic pressure up to 16 kbar. In addition
magnetization and ferromagnetic resonance (FMR) measurements were performed.
FMR and magnetization data reveal a pronounced magnetic anisotropy, which
develops below the Curie temperature, , and increases strongly
towards lower temperatures. Increasing the Cu concentration reduces this
effect. At temperatures below 35 K the magnetoresistance, , exhibits a strong dependence on the direction of the
magnetic field, probably due to an enhanced anisotropy. Applying the field
along the hard axis leads to a change of sign and a strong increase of the
absolute value of the magnetoresistance. On the other hand the
magnetoresistance remains positive down to lower temperatures, exhibiting a
smeared out maximum with the magnetic field applied along the easy axis. The
results are discussed in the ionic picture using a triple-exchange model for
electron hopping as well as a half-metal utilizing a band picture.Comment: some typos correcte
Detailed comparison of the pp -> \pi^+pn and pp -> \pi^+d reactions at 951 MeV
The positively charged pions produced in proton-proton collisions at a beam
momentum of 1640 MeV/c were measured in the forward direction with a high
resolution magnetic spectrograph. The missing mass distribution shows the bound
state (deuteron) clearly separated from the continuum. Despite the very
good resolution, there is no evidence for any significant production of the
system in the spin-singlet state. However, the cross section ratio is about twice as large as
that predicted from -wave final-state-interaction theory and it is suggested
that this is due to -state effects in the system.Comment: 8 pages, 3 figure
A retrospective of the GREGOR solar telescope in scientific literature
In this review, we look back upon the literature, which had the GREGOR solar
telescope project as its subject including science cases, telescope subsystems,
and post-focus instruments. The articles date back to the year 2000, when the
initial concepts for a new solar telescope on Tenerife were first presented at
scientific meetings. This comprehensive bibliography contains literature until
the year 2012, i.e., the final stages of commissioning and science
verification. Taking stock of the various publications in peer-reviewed
journals and conference proceedings also provides the "historical" context for
the reference articles in this special issue of Astronomische
Nachrichten/Astronomical Notes.Comment: 6 pages, 2 color figures, this is the pre-peer reviewed version of
Denker et al. 2012, Astron. Nachr. 333, 81
Efficient Passive ICS Device Discovery and Identification by MAC Address Correlation
Owing to a growing number of attacks, the assessment of Industrial Control
Systems (ICSs) has gained in importance. An integral part of an assessment is
the creation of a detailed inventory of all connected devices, enabling
vulnerability evaluations. For this purpose, scans of networks are crucial.
Active scanning, which generates irregular traffic, is a method to get an
overview of connected and active devices. Since such additional traffic may
lead to an unexpected behavior of devices, active scanning methods should be
avoided in critical infrastructure networks. In such cases, passive network
monitoring offers an alternative, which is often used in conjunction with
complex deep-packet inspection techniques. There are very few publications on
lightweight passive scanning methodologies for industrial networks. In this
paper, we propose a lightweight passive network monitoring technique using an
efficient Media Access Control (MAC) address-based identification of industrial
devices. Based on an incomplete set of known MAC address to device
associations, the presented method can guess correct device and vendor
information. Proving the feasibility of the method, an implementation is also
introduced and evaluated regarding its efficiency. The feasibility of
predicting a specific device/vendor combination is demonstrated by having
similar devices in the database. In our ICS testbed, we reached a host
discovery rate of 100% at an identification rate of more than 66%,
outperforming the results of existing tools.Comment: http://dx.doi.org/10.14236/ewic/ICS2018.
"Safe" Coulomb Excitation of 30Mg
We report on the first radioactive beam experiment performed at the recently
commissioned REX-ISOLDE facility at CERN in conjunction with the highly
efficient gamma spectrometer MINIBALL. Using 30Mg ions accelerated to an energy
of 2.25 MeV/u together with a thin nat-Ni target, Coulomb excitation of the
first excited 2+ states of the projectile and target nuclei well below the
Coulomb barrier was observed. From the measured relative de-excitation gamma
ray yields the B(E2; 0+ -> 2+) value of 30Mg was determined to be 241(31)
e2fm4. Our result is lower than values obtained at projectile fragmentation
facilities using the intermediate-energy Coulomb excitation method, and
confirms the theoretical conjecture that the neutron-rich magnesium isotope
30Mg lies still outside the ``island of inversion''
THE TOOLS AND MONTE CARLO WORKING GROUP Summary Report from the Les Houches 2009 Workshop on TeV Colliders
This is the summary and introduction to the proceedings contributions for the
Les Houches 2009 "Tools and Monte Carlo" working group.Comment: 144 Pages. Workshop site
http://wwwlapp.in2p3.fr/conferences/LesHouches/Houches2009/ . Conveners were
Butterworth, Maltoni, Moortgat, Richardson, Schumann and Skand
The cosmic web for density perturbations of various scales
We follow the evolution of galaxy systems in numerical simulation. Our goal
is to understand the role of density perturbations of various scales in the
formation and evolution of the cosmic web. We perform numerical simulations
with the full power spectrum of perturbations, and with spectrum cut at long
wavelengths. Additionally, we have one model, where we cut the intermediate
waves. We analyze the density field and study the void sizes and density field
clusters in different models. Our analysis shows that the fine structure
(groups and clusters of galaxies) is created by small-scale density
perturbations of scale \Mpc. Filaments of galaxies and clusters are
created by perturbations of intermediate scale from to \Mpc,
superclusters of galaxies by larger perturbations. We conclude that the scale
of the pattern of the cosmic web is determined by density perturbations of
scale up to \Mpc. Larger perturbations do not change the pattern of
the web, but modulate the richness of galaxy systems, and make voids emptier.
The stop of the increase of the scale of the pattern of the cosmic web with
increasing scale of density perturbations can probably be explained as the
freezing of the web at redshift .Comment: 12 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
Study of 3-prong Hadronic Decays with Charged Kaons
Using a sample of 4.7/fb integrated luminosity accumulated with the CLEO-II
detector at the Cornell Electron Storage Ring (CESR), we have measured the
branching fractions of the tau lepton into and relative to and relative to . The relative branching fractions are: (5.16+-0.20+-0.50)*,
(1.52+-0.14+-0.29)*, (2.54+-0.44+-0.39)* and at 95%
C.L., respectively. Coupled with additional experimental information, we use
our results to extract information on the structure of three-prong tau decays
to charged kaons.Comment: 16 pages postscript file also available through
http://w4.lns.cornell.edu/public/CLN
O(12) limit and complete classification of symmetry schemes in proton-neutron interacting boson model
It is shown that the proton-neutron interacting boson model (pnIBM) admits
new symmetry limits with O(12) algebra which break F-spin but preserves the
quantum number M_F. The generators of O(12) are derived and the quantum number
`v' of O(12) for a given boson number N is determined by identifying the
corresponding quasi-spin algebra. The O(12) algebra generates two symmetry
schemes and for both of them, complete classification of the basis states and
typical spectra are given. With the O(12) algebra identified, complete
classification of pnIBM symmetry limits with good M_F is established.Comment: 22 pages, 1 figur
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