Tools and Monte Carlo Session 1 (SM)

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

Contents

Tuning

Validity of tunes and Uncertainty Bands

  • Automated Tuning: Rivet & Professor
  • Can we define regions of validity for the physics implemented in the MC? e.g. What about small x, high rapidity effects
  • Can we obtain credible uncertainty bands with existing tools, or are new methods needed
  • Impact of tunes on new physics searches (with Session 2)
  • Maybe we can produce "Demystifying Tuning: A Les Houches Guide to Tuning?"

Tuning in the presence of matching

  • Chart the problem. Determine some Classic Examples.
  • How dependent on matching strategy?
  • Are there ways of revamping pre-matched tunes?
  • Influence of UE on matching

Model (in)dependence in Data/Theory Comparisons

Detector Simulation

This is joint with Session 2; for details follow this link: Tools_and_Monte_Carlo_Session_2_(BSM)#Detector_simulation_.28with_Session_1.29

Data Correction and Unfolding

At what "truth" level should data and theory generally be compared? What corrections are optimal for data to be used in MC tuning?

Issues include:

  • Jet calibration: what truth do we calibrate to? (see last Les Houches for accord on final states)
  • What is an electron? How to treat/correct for photon radiation.
  • Resonances: e.g. do we measure a Z or a lepton mass distribution?
  • Photon isolation at the truth level
  • Role of detector simulation (see Tools_and_Monte_Carlo_Session_2_(BSM)#Detector_simulation_.28with_Session_1.29 for related discussions)
  • ...



Matching

Benchmarks for Matching

  • Experimental Benchmarks
  • Theoretical Benchmarks / Pathological Observables
  • New Physics Benchmarks?

With NLO/Multileg

  • Multileg Matching at NLO, state of the field
  • What is needed for automating NLO matching?
  • Parton Showers as Phase Space Generators
  • Matching at NNLO ?
  • Things to be learned from exploring matching in N=4 SYM, etc?

Matching beyond Fixed Order

  • In High-Energy Limit (low-x)
  • Tuning in the presence of matching (see Tuning above)
  • ...

Jet Clustering Parameters for Matching

  • Possible to agree on Standard for describing, e.g. 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?

Automated Matching for BSM Processes (with Session 2)


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)

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

Jet Substructure

  • Boosted hadronic decays of massive particles (W,Z,Top,H,BSM..., with session 2)

QCD radiation patterns

  • rapidity gap definitions
  • colour flow and energy flow, coherence
  • QCD radiation patterns as a tool for reducing combinatorials in top, higgs, BSm searches...
  • Lessons from the new generation of parton showers

New Jet Algorithms

  • SM
  • Applications in BSM (with session 2)

Standard Processes for Early LHC Data

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.

List based on my poor memory, to be amended...

  • Drell-Yan (Samir Ferrag...)
  • ttbar (Rohini Godbole...)
  • W/Z ratios etc (Bruce Mellado...)
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