Tools and Monte Carlo Session 1 (SM)

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* Possibly including NLO
* Possibly including NLO
Proceedings expected. Peter to check with Leif. 8/11 wrote mail to Leif, awaiting reply.
Proceedings expected. Peter to check with Leif. 8/11 wrote mail to Leif, awaiting reply. Leif expecting contribution slightly larger than 10p.
== [[Automated ME/PS merging]] ==
== [[Automated ME/PS merging]] ==

Revision as of 16:45, 17 November 2009

Conveners present: Peter Skands, Fabio Maltoni, Jon Butterworth
(Click here for Tools and Monte Carlo Session 2 (BSM))



Automated Tuning: Rivet & Professor

Toolkit for validation of Monte Carlo event generators. Using an computationally efficient model for observable computations, Rivet provides a set of experimental analyses useful for generator sanity checks, as well as a convenient infrastructure for adding your own analyses. Rivet's design emphasises the separation between HepMC records and where they came from, allowing it to be a completely cross-generator validation platform. Rivet 1.1.3 was just released (9 June).

A rivet tutorial (Andy Buckley) was given 16:00 Thursday in the QCD room.

Proceedings expected. Joint with Professor. Joint with Important Data Sets.

Professor is a MC tuning tool, developed in Python as a set of command line programs and an underlying library. The Rivet toolkit is used to generate MC data and retrieve experimental reference data.

Proceedings joint with Rivet.

Systematic Evaluation of Errors on tunes

The title is a link.

Proceedings: check with interested parties.

Important data sets for tuning

Follow the link above.

Proceedings joint with Rivet.

Multiple Parton Interactions

  • W+jets from MPI (E. Maina, R. Chierici, S. Plaetzer, P. Skands, K. Mazumdar, S.Gieseke)
  • ttbar+jets from MPI (see ttbar+jets study; P. Bartalini et al.)

Joint proceedings? Check with authors.

Tuning in the presence of matching

Follow the link above.

Proceedings: check with piergiulio, jeppe, mario.

Model (in)dependence in Data/Theory Comparisons

Fast Detector Simulation Specification and Usage

This is joint with Session 2; see also: Tools_and_Monte_Carlo_Session_2_(BSM)#Detector_simulation_.28with_Session_1.29

Proceedings expected. Jon responsible.

Data Correction and Unfolding

No proceedings expected


A Collection of Matching Benchmarks

  • So far declared interest: F. Maltoni, P. Skands, S. Hoeche, K. Hamilton, S. Plaetzer, S. Mrenna, L. Lonnblad, P. Francavilla, J. Winter, M. Schwarz, P. Lenzi, J. Huston, J. Andersen
  • Overview of systematic studies so far (Z/W+jets, ttbar, Z->qqbar)
  • Why it's not a complete set
    • gg initial states (Higgs, with NLM Higgs)
    • Wbb in the high pT HW region (and Zbb)
    • distinguish between W+ and W- at LHC
    • QCD n-jets (P. Francavilla, S. Hoeche)
    • New Physics Benchmarks?
  • Comparison of NLO (e.g., MCFM, MC@NLO, POWHEG) with tree-level calculations (e.g., Madgraph, Alpgen, with and without showers) (e.g., for Higgs) (J. Winter, P. Lenzi)
  • Pathological Observables / Theory Tests : (P. Skands, S. Weinzierl, S. Plaetzer, K. Hamilton, M. Schwarz, ...)
    • To test Higher-Order/Higher-Log properties of matching
    • To test Coherence/Subleadling-Logs dependence on Shower Model (new PS models)
  • Complete set of observables? (not only pT and rapidity, but jet-jet correlations, jet masses, jet-jet Delta(R), etc)
  • Sensitivity to tuning (with Tuning subgroup, see Tuning in the presence of matching)

Proceedings expected on Wbb (Jon, Giacinto, Laura). Proceedings expected on ttbar + jets study (Peter to check with Frank-Peter. 8/11 mailed, awaiting reply.). Peter and Fabio to check with remaining groups.

QED/EW ME/PS Matching

  • So far declared interest: S. Gascon, F. Piccinini, C. Baty, S. Ferrag, K. Mazumdar, R. Pittau (tbc!)...

Proceedings: Peter to check with authors. 8/11 mailed Gascon and Mazumdar, awaiting replies.

LHEF for Matching

  • So far declared interest: L. Lonnblad, T. Sjostrand, F. Maltoni, S. Platzer, S. Hoeche, K. Hamilton, A. Buckley, J. Huston...
  • Possible to agree on Standard for describing, in Les Houches Event Files, properties and cuts used in ME generation that subsequent matching steps based on jet clustering would need to know about?
  • Possibly including NLO

Proceedings expected. Peter to check with Leif. 8/11 wrote mail to Leif, awaiting reply. Leif expecting contribution slightly larger than 10p.

Automated ME/PS merging

  • So far declared interest: S. Mrenna, P. Skands, S. Hoeche, K. Hamilton, S. Plaetzer
  • Automating 1st-order correction factors for showers from automatic evaluation of |M(X+1)|^2/|M(X)|^2 from an ME generator.
  • Automated merging for BSM (with session 2)

Peter to check with Plaetzer. 8/11 mailed plaetzer, awaiting reply.

Discussion on MC Uncertainties (with EX/TH and tuning subgroups)

No proceedings expected

NLO/PS Matching

Joint with multileg group.

Proceedings for Wbb, see benchmarks. Peter to check with remaining authors. 8/11 mailed out, awaiting replies.

Sector Showers

Proceedings expected. Peter responsible.

Ttbar plus jets study

Proceedings expected, joint with benchmarks, see above.

Matching Beyond Fixed Orders

Proceedings expected, see Radiation Between Jets.

Wbb in the high pT HW region

Proceedings expected, follow title link.

Parton Densities

PDFs in Monte Carlos

  • Exploring the LO* PDFs, are we ready to use them for production?
  • Uncertainty Bands for the LO* PDFs
  • PDFs and their interaction with MC tuning
  • Pythia 8 - Advantages/disadvantages of using one PDF for hard scattering ME (best cross section?) and another for evolution (universal tuning?)

Beyond LO*

  • Are PDFs ready for NLO/Multileg WG?
  • Electroweak and QCD in PDFs
  • BSM effects in PDFs (with Session 2)

Proceedings: Jon to check with Liza Mojovic on LO*.

Heavy quark PDF's

  • HQ initiated processes vis-a-vis latest implementation of HQ PDF's(Session 1)

Jet Physics

For discussion of calibration and truth level, see the session on Data/Theory comparison Tools_and_Monte_Carlo_Session_1_(SM)#Data_Correction_and_Unfolding

A very recent pedagogical review of jets, new algorithms and substructure.

No proceedings expected.

Jet Substructure

Boosted hadronic decays of massive particles (W,Z,Top,H,BSM..., with session 2) and jet mass/shape studies with QCD jets in early data.

Several Proceedings expected. Jon to check with authors.

Study of radiation between jets, for colour singlet and colour octet exchange

Proceedings Expected. Peter to hound Jeppe and Mario. 8/11 mailed Mario and Jeppe, awaiting reply.

Standard Processes for Early LHC Data (Joint with NLO/Multileg)

In the introduction session, the proposal was made that some standard processes should be listed, and in additona a subset of these should followed through the various MC and NLM sessions, to review the impact of the various issues ((N)NLO, Matching, PDFs, jet definition, EW corrections...) on the process. This is probably a cross-group activity which should be migrated to a separate page but is here for now as a reminder.


(Samir Ferrag, Stefano Moretti, Carlo Carlani... (in session 2))

Proceedings? Jon to check with Samir etc.


(Kajari Mazumdar...)

Proceedings: Jon to check with Kajari.

tt/(Z,Z+j) ratios

(Bruce Mellado...)

Preliminary results are available here

Proceedings: Jon to check with Bruce.

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