552 research outputs found
WHIZARD 2.2 for Linear Colliders
We review the current status of the WHIZARD event generator. We discuss, in
particular, recent improvements and features that are relevant for simulating
the physics program at a future Linear Collider.Comment: Talk presented at the International Workshop on Future Linear
Colliders (LCWS13), Tokyo, Japan, 11-15 November 201
Modern Particle Physics Event Generation with WHIZARD
We describe the multi-purpose Monte-Carlo event generator WHIZARD for the
simulation of high-energy particle physics experiments. Besides the
presentation of the general features of the program like SM physics, BSM
physics, and QCD effects, special emphasis will be given to the support of the
most accurate simulation of the collider environments at hadron colliders and
especially at future linear lepton colliders. On the more technical side, the
very recent code refactoring towards a completely object-oriented software
package to improve maintainability, flexibility and code development will be
discussed. Finally, we present ongoing work and future plans regarding
higher-order corrections, more general model support including the setup to
search for new physics in vector boson scattering at the LHC, as well as
several lines of performance improvements.Comment: 7 pages; contribution to the proceedings of the conference "ACAT 2014
(Advanced Computing and Analysis Techniques in physics)", Prague, Czech
Republic, September 201
Cavitation as a Microfluidic Tool
Cavitation in confined geometries in particular in narrow gaps prevalent in microfluidic geometries allows for novel applications. Here we will give an overview of successful demonstrations of cavitation as a microfluidic tool. Cavitation can pump and mix liquids very rapidly, move objects such as cells, rupture plasma membranes, probe elastic properties in micro-rheology, study coalescence, and even create arbitrary superpositions of shock waves. In all areas, bubbles are created with a focused laser which allows precise temporal and spatial control. With the usage of digital holography arbitrary configurations of bubbles can be created such as bubble clusters, squarish, toroidal, or even linear cavitation bubbles. Interestingly, even in very narrow gaps of a few tens of microns most of the bubble dynamics can be described with potential flow. This presentation will summarize published work and show current research under progress.http://deepblue.lib.umich.edu/bitstream/2027.42/84286/1/CAV2009-final103.pd
Event Generators for Bhabha Scattering
The results obtained by the "Event Generators for Bhabha Scattering" working
group during the CERN Workshop "Physics at LEP2" (1994/1995) are presented.Comment: 70 pages, PostScript file. To appear in the Report of the Workshop on
Physics at LEP2, G. Altarelli T. Sjostrand and F. Zwirner ed
Evaluation and comparison of different machine learning approaches to auditory spectro-temporal receptive field estimation
Photospheric Abundances of the Hot Stars in NGC1399 and Limits on the Fornax Cluster Cooling Flow
We present far-UV spectroscopy of the giant elliptical galaxy NGC 1399,
obtained with the Far Ultraviolet Spectroscopic Explorer. Of all quiescent
ellipticals, NGC 1399 has the strongest known ``UV upturn'' -- a sharp spectral
rise shortward of 2500 A. It is now well-established that this emission comes
from hot horizontal branch (HB) stars and their progeny; however, the chemical
composition of these stars has been the subject of a long-standing debate. For
the first time in observations of any elliptical galaxy, our spectra clearly
show photospheric metallic absorption lines within the UV upturn. The abundance
of N is at 45% solar, Si is at 13% solar, and C is at 2% solar. Such abundance
anomalies are a natural consequence of gravitational diffusion. These
photospheric abundances fall in the range observed for subdwarf B stars of the
Galactic field.
Although NGC1399 is at the center of the Fornax cluster, we find no evidence
for O VI cooling flow emission. The upper limit to 1032,1038 emission is
3.9E-15 erg/s/cm2, equivalent to 0.14 M_sun/yr, and less than that predicted by
simple cooling flow models of the NGC 1399 X-ray luminosity.Comment: 4 pages, Latex. 2 figures. Uses corrected version of emulateapj.sty
and apjfonts.sty (included). Accepted for publication in ApJ Letters. Revised
figure placemen
Far-Ultraviolet Color Gradients in Early-Type Galaxies
We discuss far-UV (1500 A) surface photometry and FUV-B color profiles for 8
E/S0 galaxies from images taken with the Ultraviolet Imaging Telescope,
primarily during the Astro-2 mission. In three cases, the FUV radial profiles
are more consistent with an exponential than a de Vaucouleurs function, but
there is no other evidence for the presence of a disk or of young, massive
stars. In all cases except M32 the FUV-B color becomes redder at larger radii.
There is a wide range of internal radial FUV-B color gradients. However, we
find no correlation between the FUV-B color gradients and internal metallicity
gradients based on Mg absorption features. We conclude that metallicity is not
the sole parameter controlling the "UV upturn component" in old populations.Comment: 11 pages; tar.gz file includes LaTeX text file, 3 PostScript figures.
Paper to be published in ApJ Letter
Pseudo-axions in Little Higgs models
Little Higgs models have an enlarged global symmetry which makes the Higgs
boson a pseudo-Goldstone boson. This symmetry typically contains spontaneously
broken U(1) subgroups which provide light electroweak-singlet pseudoscalars.
Unless such particles are absorbed as the longitudinal component of
states, they appear as pseudoscalars in the physical spectrum at the
electroweak scale. We outline their significant impact on Little Higgs
phenomenology and analyze a few possible signatures at the LHC and other future
colliders in detail. In particular, their presence significantly affects the
physics of the new heavy quark states predicted in Little Higgs models, and
inclusive production at LHC may yield impressive diphoton resonances.Comment: 28 pages, 9 figs., accepted to PRD; footnote added, typos correcte
WW Cross-sections and Distributions
We present the results obtained by the "WW Cross-sections and Distributions"
working group during the CERN Workshop "Physics at LEP2" (1994/1995)Comment: 61 pages, tar'ed gzip'ed uuencoded files, LaTeX, 4 Postscript
figures. To appear in "Physics at LEP2", G.Altarelli and F.Zwirner eds., CERN
Report 199
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