991 research outputs found
Making extreme computations possible with virtual machines
State-of-the-art algorithms generate scattering amplitudes for high-energy
physics at leading order for high-multiplicity processes as compiled code (in
Fortran, C or C++). For complicated processes the size of these libraries can
become tremendous (many GiB). We show that amplitudes can be translated to
byte-code instructions, which even reduce the size by one order of magnitude.
The byte-code is interpreted by a Virtual Machine with runtimes comparable to
compiled code and a better scaling with additional legs. We study the
properties of this algorithm, as an extension of the Optimizing Matrix Element
Generator (O'Mega). The bytecode matrix elements are available as alternative
input for the event generator WHIZARD. The bytecode interpreter can be
implemented very compactly, which will help with a future implementation on
massively parallel GPUs.Comment: 5 pages, 2 figures. arXiv admin note: substantial text overlap with
arXiv:1411.383
Probing the Noncommutative Standard Model at Hadron Colliders
We study collider signals for the noncommutative extension of the standard
model using the Seiberg-Witten maps for SU(3)_C x SU(2)_L x U(1)_Y to first
order in the noncommutativity parameters theta_munu. In particular, we
investigate the ensitivity of Z-gamma-production at the Tevatron and the LHC to
the components of theta_munu. We discuss the range of validity of this
approximation and estimate exclusion limits from a Monte Carlo simulation.Comment: 18 pages LaTeX, 23 figures. Slightly expanded introduction and
additional references. Accepted for publication in Physical Review
Clockwork SUSY: Supersymmetric Ward and Slavnov-Taylor Identities At Work in Green's Functions and Scattering Amplitudes
We study the cancellations among Feynman diagrams that implement the Ward and
Slavnov-Taylor identities corresponding to the conserved supersymmetry current
in supersymmetric quantum field theories. In particular, we show that the
Faddeev-Popov ghosts of gauge- and supersymmetries never decouple from the
physical fields, even for abelian gauge groups. The supersymmetric
Slavnov-Taylor identities provide efficient consistency checks for automatized
calculations and can verify the supersymmetry of Feynman rules and the
numerical stability of phenomenological predictions simultaneously.Comment: 12 pages, feynmp.sty. References added, minor typos corrected and
clarified the scope of the paper in the introduction, published versio
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
Cosmological and Black Hole Spacetimes in Twisted Noncommutative Gravity
We derive noncommutative Einstein equations for abelian twists and their
solutions in consistently symmetry reduced sectors, corresponding to twisted
FRW cosmology and Schwarzschild black holes. While some of these solutions must
be rejected as models for physical spacetimes because they contradict
observations, we find also solutions that can be made compatible with low
energy phenomenology, while exhibiting strong noncommutativity at very short
distances and early times.Comment: LaTeX 12 pages, JHEP.st
MadEvent: Automatic Event Generation with MadGraph
We present a new multi-channel integration method and its implementation in
the multi-purpose event generator MadEvent, which is based on MadGraph. Given a
process, MadGraph automatically identifies all the relevant subprocesses,
generates both the amplitudes and the mappings needed for an efficient
integration over the phase space, and passes them to MadEvent. As a result, a
process-specific, stand-alone code is produced that allows the user to
calculate cross sections and produce unweighted events in a standard output
format. Several examples are given for processes that are relevant for physics
studies at present and forthcoming colliders.Comment: 11 pages, MadGraph home page at http://madgraph.physics.uiuc.ed
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
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