267 research outputs found
Automated NLO QCD Corrections with WHIZARD
We briefly discuss the current status of NLO QCD automation in the Monte
Carlo event generator WHIZARD. The functionality is presented for the explicit
study of off-shell top quark production with associated backgrounds at a lepton
collider.Comment: 9 pages, 5 figures, to appear in the proceedings of the European
Physical Society Conference on High Energy Physics 2015 (EPS-HEP 2015),
Vienna, Austria, 22nd to 29th of July 201
Matching NLO QCD Corrections in WHIZARD with the POWHEG scheme
Building on the new automatic subtraction of NLO amplitudes in WHIZARD, we
present our implementation of the POWHEG scheme to match radiative corrections
consistently with the parton shower. We apply this general framework to two
linear collider processes, and
.Comment: 7 pages, 4 figures, to appear in the proceedings of the European
Physical Society Conference on High Energy Physics 2015 (EPS-HEP 2015),
Vienna, Austria, 22nd to 29th of July 201
QCD NLO with Powheg matching and top threshold matching in WHIZARD
We present the status of the automation of NLO processes within the event
generator WHIZARD. The program provides an automated FKS subtraction and phase
space integration over the FKS regions, while the (QCD) NLO matrix element is
accessed via the Binoth Les Houches Interface from an externally linked
one-loop program. Massless and massive test cases and validation are shown for
several e+e- processes. Furthermore, we discuss work in progress and future
plans. The second part covers the matching of the NRQCD prediction with NLL
threshold resummation to the NLO continuum top pair production at lepton
colliders. Both the S-wave and P-wave production of the top pair are taken into
account in the resummation. The inclusion in WHIZARD allows to study more
exclusive observables than just the total cross section and automatically
accounts for important electroweak and relativistic corrections in the
threshold region.Comment: 9 pages, 3 figures, Talk given at 12th International Symposium on
Radiative Corrections (Radcor 2015) and LoopFest XIV (Radiative Corrections
for the LHC and Future Colliders); v2: reference adde
Automation of NLO processes and decays and POWHEG matching in WHIZARD
We give a status report on the automation of next-to-leading order processes
within the Monte Carlo event generator WHIZARD, using GoSam and OpenLoops as
provider for one-loop matrix elements. To deal with divergences, WHIZARD uses
automated FKS subtraction, and the phase space for singular regions is
generated automatically. NLO examples for both scattering and decay processes
with a focus on e+e- processes are shown. Also, first NLO-studies of
observables for collisions of polarized leptons beams, e.g. at the ILC, will be
presented. Furthermore, the automatic matching of the fixed-order NLO
amplitudes with emissions from the parton shower within the POWHEG formalism
inside WHIZARD will be discussed. We also present results for top pairs at
threshold in lepton collisions, including matching between a resummed threshold
calculation and fixed-order NLO. This allows the investigation of more
exclusive differential observables.Comment: 5 pages, 3 figures, Talk presented at ACAT 2016 at UTFSM,
Valpara\'iso, Chil
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
Top Physics in WHIZARD
In this talk we summarize the top physics setup in the event generator
WHIZARD with a main focus on lepton colliders. This includes full six-, eight-
and ten-fermion processes, factorized processes and spin correlations. For
lepton colliders, QCD NLO processes for top quark physics are available and
will be discussed. A special focus is on the top-quark pair threshold, where a
special implementation combines a non-relativistic effective field theory
calculation augmented by a next-to-leading threshold logarithm resummation with
a continuum relativistic fixed-order QCD NLO simulation.Comment: 6 pages, 2 figures, Talk presented at the International Workshop on
Future Linear Colliders (LCWS15), Whistler, Canada, 2-6 November 201
Local-look navigator gated and cardiac triggered echo-planar spectroscopic imaging of the heart
DOES FREE DISTRIBUTION OF MOSQUITO NETS AFFECT SUBSIDIZED NET SALES? EVIDENCE FROM A NATIONWIDE CAMPAIGN IN TANZANIA
Randomized controlled trials (RCTs) are increasingly popular for assessing development programmes. This study investigates the validity of extrapolating RCT results to large-scale programmes, using the example of the national bed net subsidy programme in Tanzania that later added a free distribution campaign. Although the RCTs suggest steady sales of nets throughout, an interrupted time series model reveals a 34 per cent monthly decline immediately after the campaign compared to 'normal' sales. After 6months, the total unsold nets reached 45 per cent of normal sales, or 347000 nets nationwide. We hypothesize that these differences in results arise from various scale and spillover effects. © 2013 John Wiley & Sons, Ltd
METHOD EVALUATION TO DETERMINE HYDRATION STATES OF TENDONS BY USING MRI
Due to the fact that water content is a determinant of the material properties of tendons and therefore might affect sports performance and the risk of injury, the purpose of this pilot study was to evaluate the reliabilityand sensitivity of a MRI based method to quantify content of a tendon. For this pilot study twenty porcine digital flexor tendons were chosen. All samples were examined on a MR scanner using three 3D ultra-short echo time sequences. With the applied sequences it was possible to determine a decrease in water content of the tendons. In addition, the methods showed a good inter session reliability. Further investigations are needed to improve the upper and lower limit of resolution regarding the physiological hydration state
Developing Hyperpolarized 13C Spectroscopy and Imaging for Metabolic Studies in the Isolated Perfused Rat Heart
Hyperpolarized 13C magnetic resonance is a powerful tool for the study of cardiac metabolism. In this work, we have implemented protocols for the real-time hyperpolarized 13C investigation of Langendorff-perfused rat hearts using both non-selective non-localized spectroscopy and fast spectroscopic imaging. Following [1-13C] pyruvate infusion, we observed both catabolic and anaplerotic metabolic processes resulting in a number of metabolites, including bicarbonate, carbon dioxide, lactate, alanine and aspartate. Employing fast spectroscopic imaging, we were able to observe regional variations in pyruvate perfusion as well as in lactate and bicarbonate productio
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