Key Points
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1 - Matrix Element Generator
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MadGraph is a widely used tool to generate matrix-element predictions for the hard scatter for SM and BSM processes.
Standalone MadGraph can run interactively on-the-fly or by importing the predefined text scripts
Gridpacks are used for large scale productions with consistency guaranteed
LHE level information is not physical and parton shower is needed to describe full physics
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2 - Parton Shower Generator
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Pythia8 is the main tool used for parton showering in CMS
Events are not physical if it did not go through parton shower
Jet merging is a technique to avoid double countings of jet phase spaces in ME and PS calculations
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3 - Analysis and systematic uncertainties
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PDF uncertainties can be estimated from a set of different per-event weights. The method depends on the type of PDF set that is used (hessian, MC replicas)
Scale and alphaS variations are another source of uncertainty in the prediction of a simulated sample and can be used to estimate systematic uncertainties
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4 - CMS resources for samples and generators
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DAS can be used to find samples and their files, number of events for a certain sample etc
McM is used for sample generation management, and can be used by the user to obtain additional information about their samples, e.g. the root gridpack, fragments etc.
McM is also a good place to look for example cmsDriver commands
Different sources for x-secs exist within CMS: a CMSSW analyzer and a database
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Glossary
A reference document for information and explanations of acronyms and common terms in the CMS computing, grid-computing, detector, high energy physics and analysis environments.
The WorkBook Glossary is continually being updated with new and improved definitions of acronyms and concepts relating to the CERN, the CMS experiment, the LHC and GRID computing.