Tuning in the presence of matching
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| + | '''Interested parties''': ''Piergiulio Lenzi, Vitaliano Ciulli, Peter Skands, Leif Lonnblad, Simon Platzer, Jon Butterworth, Jeppe Anderson, Mario Campanelli, Markus Warsinsky, Matthew Schwartz, Peter Loch, Dieter Zeppenfeld, Giacinto Piacquadio, Paulo Francovilla +...'' | ||
| + | == Chart the problem. Determine some Classic Examples == | ||
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| + | [http://www.slac.stanford.edu/spires/find/hep/www?eprint=arXiv:0903.3918 Effect of ME corrections] on low pT end of the Z pT distribution compared for PYTHIA, HERWIG, Sherpa, Alpgen. Some points: | ||
| + | * Affect n=1 ME corrections, Pythia, Herwig, Alpgen+Herwig and Sherpa all pretty much agree. For Algen+Pythia there is a significant difference at low pT. Means that PYTHIA tune would be different for usage with & without Alpgen. | ||
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| + | Piergiulio Lenzi [http://hep.fi.infn.it/CMS/Florence_integration/giulio/LesHouches/lenzi_13062009.pdf slides] | ||
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| + | == How would low x logs/high energy limit affect tunes? == | ||
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| + | Expect extra events at with high rapidity jets due to: | ||
| + | * large colour singlet contribution. This will have a component with rapidity gaps, and a component where these gaps have been destroyed by UE. | ||
| + | * large colour octet contribution enhanced by low x logs (Jeppes's calculations). | ||
| + | Presumably these effects will distort min bias tunes etc, since this physics is not necessarily in the MC. The first effect actually can be modelled by HERWIG+JIMMY, to some extent at least. | ||
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| + | Not addressed: | ||
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| + | * How dependent on matching strategy? | ||
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| + | * Are there ways of revamping pre-matched tunes? | ||
Current revision
Interested parties: Piergiulio Lenzi, Vitaliano Ciulli, Peter Skands, Leif Lonnblad, Simon Platzer, Jon Butterworth, Jeppe Anderson, Mario Campanelli, Markus Warsinsky, Matthew Schwartz, Peter Loch, Dieter Zeppenfeld, Giacinto Piacquadio, Paulo Francovilla +...
Chart the problem. Determine some Classic Examples
Effect of ME corrections on low pT end of the Z pT distribution compared for PYTHIA, HERWIG, Sherpa, Alpgen. Some points:
- Affect n=1 ME corrections, Pythia, Herwig, Alpgen+Herwig and Sherpa all pretty much agree. For Algen+Pythia there is a significant difference at low pT. Means that PYTHIA tune would be different for usage with & without Alpgen.
Piergiulio Lenzi slides
How would low x logs/high energy limit affect tunes?
Expect extra events at with high rapidity jets due to:
- large colour singlet contribution. This will have a component with rapidity gaps, and a component where these gaps have been destroyed by UE.
- large colour octet contribution enhanced by low x logs (Jeppes's calculations).
Presumably these effects will distort min bias tunes etc, since this physics is not necessarily in the MC. The first effect actually can be modelled by HERWIG+JIMMY, to some extent at least.
Not addressed:
- How dependent on matching strategy?
- Are there ways of revamping pre-matched tunes?
