595 research outputs found
2nd International Workshop on Software Engineering, Artificial Intelligence and Expert Systems for High-energy and Nuclear Physics: New Computing Techniques in Physics Research
No full textxv, 785 hlm. : ilus. ; tab. ; 23 cm
from LEP to linear collider energies
No full text18 pages, uses epsfig.sty, 10 postscript figures. revised for minor change of the text at Dec 6 1994The complete tree level cross section for the process is computed using the GRACE system, a program package for automatic amplitude calculation. Special attention is brought to the gauge violation problem induced by the finite width of the -boson. The {\it preserved gauge scheme} is introduced and an event generator which includes double-resonant, single-resonant and non-resonant diagrams with no need for a cut on the electron polar angle is presented. Since no cut needs to be applied to the electron, the generator can be used to estimate background for searches involving jets and missing energy. A monojet event rate estimation based on this process at LEP-I energy is discussed
Computational Particle Physics for Event Generators and Data Analysis
No full text19 pages, 11 figures, Proceedings of CCP (Conference on Computational Physics) Oct. 2012, Osaka (Japan) in IOP Journal of Physics: Conference SeriesInternational audienceHigh-energy physics data analysis relies heavily on the comparison between experimental and simulated data as stressed lately by the Higgs search at LHC and the recent identification of a Higgs-like new boson. The first link in the full simulation chain is the event generation both for background and for expected signals. Nowadays event generators are based on the automatic computation of matrix element or amplitude for each process of interest. Moreover, recent analysis techniques based on the matrix element likelihood method assign probabilities for every event to belong to any of a given set of possible processes. This method originally used for the top mass measurement, although computing intensive, has shown its power at LHC to extract the new boson signal from the background. Serving both needs, the automatic calculation of matrix element is therefore more than ever of prime importance for particle physics. Initiated in the eighties, the techniques have matured for the lowest order calculations (tree-level), but become complex and CPU time consuming when higher order calculations involving loop diagrams are necessary like for QCD processes at LHC. New calculation techniques for next-to-leading order (NLO) have surfaced making possible the generation of processes with many final state particles (up to 6). If NLO calculations are in many cases under control, although not yet fully automatic, even higher precision calculations involving processes at 2-loops or more remain a big challenge. After a short introduction to particle physics and to the related theoretical framework, we will review some of the computing techniques that have been developed to make these calculations automatic. The main available packages and some of the most important applications for simulation and data analysis, in particular at LHC will also be summarized
Concluding remarks : Emerging topics
No full textIn summing up this workshop, we would like to open a broad discussion on additional emerging topics that may contribute to shape the future of physics research computing activities. To initiate this global discussion let me address in this short contribution some of these issues: distributed public computing, social or collaborative software, web computing, high precision numerical computation, common development platforms and languages issues. We welcome contributions to this discussion on the ACAT Twiki web site
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