1. Monte Carlo Generators in CMS on behalf of the CMS collaboration 1. Overlook & requirements 2. Tuning & physics validation 3. Strategies in production Paolo Bartalini National Taiwan University ACAT08 - November 4 th 2008

2. 2 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Overlook & requirements The LHC physics needs The LHC physics needs Main MC choices by CMS Main MC choices by CMS General input settings General input settings Software integration strategy Software integration strategy Organization Organization The Monte Carlo generators in CMS

3. 3 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08Introduction The Monte Carlo generators for the LHC are unavoidable simulation tools to The Monte Carlo generators for the LHC are unavoidable simulation tools to prepare (design, commission) the detector and the trigger systems prepare (design, commission) the detector and the trigger systems practice the analyses estimating their physics reach practice the analyses estimating their physics reach interpret/understand the forthcoming data CURRENT FOCUS OF THE CMS EXPERIMENT interpret/understand the forthcoming data CURRENT FOCUS OF THE CMS EXPERIMENT The work related to the MC generators naturally develops The work related to the MC generators naturally develops at the interface between the experimental, the theoretical and the software communities with several interplays between them which determine a privileged communication area MC cahier the charges for LHC experimentalists: MC cahier the charges for LHC experimentalists: collect and interpret the generator requirements of the analysis groups collect and interpret the generator requirements of the analysis groups communicate and collaborate with the MC theory community communicate and collaborate with the MC theory community build a coherent generation for doing physics build a coherent generation for doing physics steer the generator tuning with data steer the generator tuning with data integrate, validate, maintain the generator in the experiment’s software framework integrate, validate, maintain the generator in the experiment’s software framework PH SW Theory Generators Production Simulation Physics CMS

4. 4 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Physics requirements Extra gluon emission described with ME at the highest possible order (+matching). Spin correlations needed Interface to dedicated tools may be needed. Tuning with data is essential Interface to dedicated tools may be needed. Tuning with data necessary MPI desirable Tuning with data needed The MC description of LHC events is tremendously tremendouslycomplex Other desirable features, from the experimentalist’s viewpoint: output in the Les Houches standard format output in the Les Houches standard format as much complete as possible coverage of SM phase space as much complete as possible coverage of SM phase space user friendly inclusion of new physics signals user friendly inclusion of new physics signals support support

5. 5 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 General purpose generators & decay tools in CMS Latest FORTRAN event generator version, moving to the newest C++ versions Latest FORTRAN event generator version, moving to the newest C++ versions PYTHIA6, HERWIG extensively used as baseline event generators (SM, BSM) and for PS/fragmentation from external MEs extensively used as baseline event generators (SM, BSM) and for PS/fragmentation from external MEs PYTHIA8, HERWIG++ being used in parallel. First central productions recently performed in CMS! being used in parallel. First central productions recently performed in CMS!SHERPA interfaced. Currently being validated. Not used in production yet interfaced. Currently being validated. Not used in production yet Several decay tools are used (work with all the supported general purpose MCs) Several decay tools are used (work with all the supported general purpose MCs) TAUOLA (  decays) TAUOLA (  decays) used where the description of  decays is relevant used where the description of  decays is relevant PHOTOS (QED corrections) used where real QED description in simple process important used where real QED description in simple process important EvtGen (for B hadron decays) EvtGen (for B hadron decays) used only in signal description used only in signal description

6. 6 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Parton level generators at the LHC LO, NLO QCD description of most of the SM and BSM physics processes Enormous progress in the recent years PYTHIA, HERWIG: 2→1, 2, 3 LO ME PYTHIA, HERWIG: 2→1, 2, 3 LO ME reference for QCD production, (PYTHIA also for BSM) reference for QCD production, (PYTHIA also for BSM) Alpgen, MadEvent/MadGraph, SHERPA, HELAC: 2→2(+3, 4) LO ME Alpgen, MadEvent/MadGraph, SHERPA, HELAC: 2→2(+3, 4) LO ME ME-PS matching (MLM, CKKW) to higher LO diagrams (up to four additional q,g jets) ME-PS matching (MLM, CKKW) to higher LO diagrams (up to four additional q,g jets) ALPGEN, MadGraph are ME reference generators for high p T physics ALPGEN, MadGraph are ME reference generators for high p T physics SHERPA being validated SHERPA being validated Interest in HELAC Interest in HELAC POWHEG, MC@NLO: NLO ME, many process implemented, in continuous evolution POWHEG, MC@NLO: NLO ME, many process implemented, in continuous evolution With ME-PS matching to NLO With ME-PS matching to NLO MC@NLO reference generator for top and electroweak physics MC@NLO reference generator for top and electroweak physics Extreme interest in POWHEG, under validation Extreme interest in POWHEG, under validation CompHEP: 2→n LO ME CompHEP: 2→n LO ME CompHEP used for Zbb and multi-jet CompHEP used for Zbb and multi-jet TopRex, SingleTop: dedicated 2→2, 3 LO ME TopRex, SingleTop: dedicated 2→2, 3 LO ME used for top physics in the recent past used for top physics in the recent past Phantom: full 2→6 LO ME Phantom: full 2→6 LO ME used for crosschecks used for crosschecks

7. 7 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Tools for shower+hadronisation: PYTHIA primary choice (6.4 series), HERWIG (6.5 series) useful crosscheck (and used for MC@NLO). Growing interest for Sherpa. PYTHIA: CMS uses old Q 2 ordered shower new (p T ordered) showers still need more validation/tuning against Tevatron jet data new (p T ordered) showers still need more validation/tuning against Tevatron jet data PDF settings: LO PDF CTEQ6L1 (LHAPDF=10042). NLO PDF used only for NLO generators and for determining errors. Need iterations to tune PDF with the use of LHC data. PS radiation and fragmentation (b, light quarks) settings: used from LEP tunings (see for instance CMS note 2005/013). Need to re-tune to LHC data. Maybe a different approach necessary when using external ME to Parton Showers? Underlying Event (see Tune tables in backup slides) D6T tuning (by R. Field), using CDF data and default extrapolation at LHC energies + some guidelines to evaluate the uncertainties (for example impact on isolation observables) Default tunes for HERWIG/Jimmy General reference MC settings CTEQ5L CTEQ6L CTEQ6M R. Field Several Interplays between these seemingly different settings! CEDAR tools evaluated (See talk of A.Buckley )

8. 8 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 CMS prefers generators integrated in the experiment software: directly used in production. CMS prefers generators integrated in the experiment software: directly used in production. The usage of the LCG GENSER guarantee The usage of the LCG GENSER guarantee code blessed by the authors, ported/tested on the necessary platforms and a first systematic basic sanity check (See talk of M.Kirsanov) Then each generator interfaced Then each generator interfaced to CMSSW must undergo: a technical validation to show a technical validation to show its ability to run standalone and in production a physics validation wrt a a physics validation wrt a similar content generator Methods also exist to start from Methods also exist to start from an externally produced parton level (LHE) file. LCG MCDB evaluated LCG MCDB evaluated (see talk of S.Belov) Software integration strategy GenerationSimulation (Generation)+Showering+Hadronisation+Decay Reconstruction Registration Data Base CMS production [C. Saout]

9. 9 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Conveners (joint appointments in the Physics and in the Software groups) → Paolo Bartalini - NTU → Roberto Chierici - IPNL-Lyon Coordination of the Monte Carlo generators’ validation (including the software framework) → Stephen Mrenna - Fermilab → Avto Kharchilava - Buffalo Coordination of the Monte Carlo generators’ integration in the CMS software → Julia Yarba – Fermilab Responsible of the particle properties in the CMS software → Todd Adams - Florida State One integrator per each supported Monte Carlo generator package One representative per each physics “analysis” (or “object”) group Organization of the CMS Monte Carlo generators group

10. 10 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Tuning & physics validation (few use cases) Multiple Parton Interactions and Underlying Event tunes Multiple Parton Interactions and Underlying Event tunes Double Parton Scattering as a benchmark for Pythia8/Herwig++ validation Double Parton Scattering as a benchmark for Pythia8/Herwig++ validation Matrix Element-Parton Shower vs Next to Leading Order in the top sector Matrix Element-Parton Shower vs Next to Leading Order in the top sector Monte Carlo Generators in CMS

11. 11 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 ISR, FSR, SPECTATORS… Not enough to account for the observed multiplicities & P T spectra The Pythia solution: [T. Sjöstrand et al. PRD 36 (1987) 2019] Multiple Parton Interactions (MPI) (now available in other general purpose MCs: Herwig/Jimmy, Sherpa, etc.) Inspired by observations of double high P T scatterings pQCD Models Main Parameter: P T cut-off P T0 Cross Section Regularization for P T  0 P T0 ~ inverse of effective colour screening length =  parton-parton /  proton-proton Controls the number of interactions hence the Multiplicity: =  parton-parton /  proton-proton N cc,pT ch Tuning for the LHC (emphasis on the Energy-dependence of the parameters) MB N cc,pT ch  (dampening) Multiple Parton Interactions d Impact Parameter Introduce IP correlations in Multiple Parton Interactions  Describe Tails! Pythia MPI Model with Varying impact parameter between the colliding hadrons: hadronic matter is described by Gaussians Further correlations introduced in new Pythia MPI [Eur.Phys.J.C39(2005)129 + JHEP03(2004)053] Recent MB data from CDF available vs vs

12. 12 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 The Calo jet (or Charged jet) provides a scale and defines a direction in the  plane The transverse region is expected to be particularly sensitive to the UE Several Jet topologies can be tested to increase the sensitiveness to the MPI component of the UE MB and Jet events observables are the same The P T of the boson is used to define a direction “Toward” “Away” “Transverse” Jet #1 Direction ΔΔ “Transverse” Region “Toward” Region “Transverse” Region “Away” Region “Away” Region jet1 -2 2  0 22  DY events Main observables built from charged tracks: + dN/dd, charged density + d(PT sum )/dd, energy density LHC experiments have a much wider  region with respect to the Tevatron ones Early CMS MPI Tuning on Underlying Event Observables

13. 13 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 → discriminate DW against DWT DWT DW DWT DW Select charged tracks in | η | 0.9 GeV/c CMS Preliminary ∫ L dt = 100 pb -1 Herwig “Soft UE” CMS Physics Analysis Summary QCD- 07-003 + Pythia Tune DW (=.125) OLD MPI, IP CORRELATIONS, ~ TUNE A + Pythia Tune DWT (=0.08) DW with default PT-cut-off evolution + Pythia Tune S0 (=0.08) P.Skands, New MPI, P.Skands, New MPI, colour-flow All these Pythia tunes describe MB & UE at Tevatron. Further information in backup slides. -> UE in the transverse region Herwig “Soft UE” (input to RECO is DWT) Early CMS MPI Tunes

14. 14 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 (input to RECO is DWT) CMS Preliminary ∫ L dt = 100 pb -1 ‣ Ratios between uncorrected UE-observables: UE-density(p T (track) > 0.9 GeV/c) / UE-density(p T (track) > 1.5 GeV/c) ‣ No additional track reconstruction corrections needed! track reconstruction performance uniform in p T for p T > 0.9 GeV/c → discriminate DW/DWT against S 0 CMS Physics Analysis Summary QCD- 07-003 UE Ratios in the transverse region Early CMS MPI Tunes

15. 15 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Double Parton Scattering and PYTHIA8/Herwig++ validation DP Component [F.Bechtel] Currently extending these DP studies to double boson, multi-HF, etc.

16. 16 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Validating ME-PS vs PS in top physics p T (tt)  (t-t) t t g t t g g t t g g g Large differences in transverse variables related to radiation Large effects at high p T (tt)=p T (radiation) Large effects at high p T (tt)=p T (radiation) Average p T (tt)~60-70 GeV ! Average p T (tt)~60-70 GeV ! 40% probability that a tt system recoils against a radiation larger than 50 GeV 40% probability that a tt system recoils against a radiation larger than 50 GeV → effect on reconstruction → Mandatory to use the same strategies for physics backgrounds like W/Z+Njets [T. Le Grand, R.Chierici]

17. 17 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 ALPGEN vs MadGraph with matching p T (tt)  (t-t) ALPGEN and MadGraph differ by at most 50% on the p T prediction Important to understand the residual theory error on the distributions: Effect of renormalisation and factorisation scales on the predictions Effect of renormalisation and factorisation scales on the predictions Effect of the chosen ME-PS matching scale Effect of the chosen ME-PS matching scale Excellent agreement on other variables  (t)

18. 18 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Matched vs MC@NLO Comparisons to MC@NLO ongoing in CMS. Conceptual difficulties in interpreting the results: Non perturbative part treated by HERWIG/JIMMY. Non perturbative part treated by HERWIG/JIMMY. Should compare to a matched tt0j(exc)+tt1j(inc) Should compare to a matched tt0j(exc)+tt1j(inc) production production Still a very important step in understanding high p T radiation and increase our confidence in the process description. Also gives indications on: Relative importance of first emission Relative importance of first emission Normalization Normalization Indication of systematic errors associated to the description of radiation. Indication of systematic errors associated to the description of radiation. Essential agreement in the p T (tt) tail. Good agreement in other distributions. Preliminary generator level study

19. 19 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 The importance of the ME tools A parton shower is by construction an highly tunable tool. For a matched calculation the effect of tunings in the hard regions are less relevant because this is described by the Matrix Element more predictive power more predictive power less sensitivity to the MC tunings less sensitivity to the MC tunings systematic errors due to theory/modelling are smaller (should include theory uncertainties of the matching itself) systematic errors due to theory/modelling are smaller (should include theory uncertainties of the matching itself) F. Maltoni, top 2008

20. 20 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Strategies in production Choice of the reference generators Choice of the reference generators Current and future massive productions Current and future massive productions Conclusions Conclusions Monte Carlo Generators in CMS

21. 21 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 MC Production: General generation criteria Bulk constituted by “complete” set of SM processes Bulk constituted by “complete” set of SM processes → Sufficient ME description (with the “signals” in mind) → Coherent PS, fragmentation, decay → Homogeneous set of parameters (PDFs etc.) → Tuned UE (Use LHC data as soon as possible) SM NP Main SUSY and BSM points to train analyses Main SUSY and BSM points to train analyses → compare SM and BSM on a possibly equal footing including SM-SM and even SM-BSM interference Increase the SM statistics on the tails Increase the SM statistics on the tails → Region of interest defined in the light of the signal patterns Redundancy in crucial portions of phase space Redundancy in crucial portions of phase space → Different generators, NLO, etc. → Different PS (Systematic variation of other parameters & tunes is typically addressed outside the central production) Centralized MC productions should cover most of the physics simulation needs of the collaboration Centralized MC productions should cover most of the physics simulation needs of the collaboration → Current emphasis on the physics goals with the first 100 pb -1 → Practicing the analyses assessing their physics reach → Commissioning the trigger system, etc.

22. 22 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 MC Production: choice of the reference generators The CMS way: MadGraph +PYTHIA as a reference ME generator for both SM and BSM → can treat all phase space coherently, including SM+BSM interferences → do not give up higher leading order matched QCD contribution → flexibility of including any new physics Further details here: http://cp3wks05.fynu.ucl.ac.be/twiki/bin/view/Library/MadGraphSamples Matching: here pass events to experiment software Definition of different portions of phase space in collaboration with the MadGraph/MadEvent team, with theory-validated LHE files and corresponding binaries for Monte Carlo productions. → Agree on the file contents (processes, cuts, settings) Large scale SM Production successfully accomplished in 2008, now moving toward the BSM points using the same tools/procedures + Use ALPGEN +PYTHIA and MCatNLO +HERWIG as primary comparisons for the analyses

23. 23 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 “Signals” (SM small cross-sections, BSM, Higgs) also handled outside central prod. Made with PYTHIA, ALPGEN, MC@NLO “Signals” (SM small cross-sections, BSM, Higgs) also handled outside central prod. Made with PYTHIA, ALPGEN, MC@NLO MadGraph, ME-PS matching PYTHIA p T hat bins for QCD p T hat bins for QCD Recent MC production efforts in CMS A full detector simulation, corresponding to a total of 200M events. A full detector simulation, corresponding to a total of 200M events. Min bias (40 Mevt), QCD (light/b) (30 Mevt) and  +jets (10 Mevt) Min bias (40 Mevt), QCD (light/b) (30 Mevt) and  +jets (10 Mevt) Electrons/muons from b or in-flight decays (25/40 Mevt) Electrons/muons from b or in-flight decays (25/40 Mevt) Drell-Yan and Onia (10 Mevt) Drell-Yan and Onia (10 Mevt) QCD (light/b) (plus jets) (30 Mevt) and  +jets (5 Mevt) QCD (light/b) (plus jets) (30 Mevt) and  +jets (5 Mevt) W/Z (+j) (10 Mevt), others EWK (VVj, Wc, VQQ,  *+j, Z→ ) (10 Mevt) W/Z (+j) (10 Mevt), others EWK (VVj, Wc, VQQ,  *+j, Z→ ) (10 Mevt) Top (2 Mevt) Top (2 Mevt) +500K  +jets with PYTHIA8 +500K  +jets with PYTHIA8 5M QCD with HERWIG++ 5M QCD with HERWIG++ +700K single diffractive with POMWIG +700K single diffractive with POMWIG 1M EWK+Top with MC@NLO 1M EWK+Top with MC@NLO Very large fast simulation production (~600M events), corresponding to 3-6 months of data taking ay 20% efficiency and 300 Hz rate to storage. Very large fast simulation production (~600M events), corresponding to 3-6 months of data taking ay 20% efficiency and 300 Hz rate to storage. More than 400M are QCD. H T binning for jets and  +jets needed to enhance tails. More than 400M are QCD. H T binning for jets and  +jets needed to enhance tails. Matched productions organized in “cocktails”, with all parton multiplicities together in the same Matched productions organized in “cocktails”, with all parton multiplicities together in the same dataset and with the right proportion. dataset and with the right proportion. MBPYTHIA100Mtt+jetsMadGraph +PYTHIA 10M QCD jets MadGraph +PYTHIA 217MW+jets MadGraph +PYTHIA 63M MB bb PYTHIA 21M Z+jets MadGraph +PYTHIA 5M QCD bb Madgraph +PYTHIA 23M  +jets MadGraph +PYTHIA 35M QCD jets PYTHIA 45M  +jets PYTHIA 4M QCD e.m.PYTHIA 33M Generation for validation

24. 24 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08Summary Big time for Monte Carlo generators at the LHC Big time for Monte Carlo generators at the LHC Very active EXP, TH and SW communities: progress in MC studies, MC development, MC support Very active EXP, TH and SW communities: progress in MC studies, MC development, MC support CMS emphasis on the interpretation of the first data CMS emphasis on the interpretation of the first data Physics- and Software-wise CMS Monte Carlo organization in place Physics- and Software-wise CMS Monte Carlo organization in place MC validation, integration, maintenance and production policies defined MC validation, integration, maintenance and production policies defined Privileged view and communication toward external TH and SW entities in the same area (LCG, CEDAR, MadGraph) Privileged view and communication toward external TH and SW entities in the same area (LCG, CEDAR, MadGraph) The year 2008 has achieved various ambitious MC milestones in the central CMS production, preparing the ground for further developments in the next years The year 2008 has achieved various ambitious MC milestones in the central CMS production, preparing the ground for further developments in the next years Complete, consistent and coherent generation of SM and BSM processes with MadGraph Complete, consistent and coherent generation of SM and BSM processes with MadGraph Successful integration and usage of several complementary Monte Carlo generators, including Herwig++ and Pythia8 Successful integration and usage of several complementary Monte Carlo generators, including Herwig++ and Pythia8 Huge progress in CMS tuning and physics validation activities Huge progress in CMS tuning and physics validation activities Ready to tune the Multiple Parton Interactions models of the general purpose MC generators on the first LHC data Ready to tune the Multiple Parton Interactions models of the general purpose MC generators on the first LHC data Systematic studies in ttbar production as well as in several other fields: test of different ME tools, different parameterizations (PDFs, etc.), NLO Systematic studies in ttbar production as well as in several other fields: test of different ME tools, different parameterizations (PDFs, etc.), NLO

25. 25 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08Credits R. Chierici, F. Ambroglini, F. Bechtel, L. Fanò, R. Field, T. Le Grand, F. Maltoni S. Mrenna, C. Saout, J. Yarba, CMS generator contacts in the analysis groups, CMS generator integrators, CMS data operations group LCG generator group, etc…

26. 26 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Backup

27. 27 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 Generators currently used per physics topic Generators currently used per physics topic The CMS physics program is very rich: Standard Model Soft QCD: PYTHIA, HERWIG Soft QCD: PYTHIA, HERWIG High p T QCD: PYTHIA, HERWIG, ALPGEN, MadGraph High p T QCD: PYTHIA, HERWIG, ALPGEN, MadGraph W+jets, Z+jets: ALPGEN, MadGraph, CompHEP, MC@NLO W+jets, Z+jets: ALPGEN, MadGraph, CompHEP, MC@NLO Top physics: ALPGEN, MadGraph, MC@NLO Top physics: ALPGEN, MadGraph, MC@NLO Diffractive physics: POMWIG, Exhume, EDDE Diffractive physics: POMWIG, Exhume, EDDE Higgs: PYTHIA Higgs: PYTHIA Beyond the Standard Model SUSY: PYTHIA, MadGraph SUSY: PYTHIA, MadGraph Exotica: PYTHIA, MadGraph, Charybdis Exotica: PYTHIA, MadGraph, Charybdis Heavy ions Hydjet, PYQUEN Hydjet, PYQUEN Detector studies Dedicated: cosmic muon generator, particle guns, beam halo and beam-gas interactions Dedicated: cosmic muon generator, particle guns, beam halo and beam-gas interactions

28. 28 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 PT0= PT0(Ecm/E0) PARP(90) Pythia CTEQ5L Tunes Current CMS reference: D6T D6T = DWT with CTEQ6L PDF and PARP(82)=1.8387

29. 29 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 MG: Phase space definitions in collaboration with F. Maltoni and the MG team

30. 30 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 MG: Setup and Input Parameter Settings Scales: set dynamically in MadGraph to m T. We should use them as our default. PDFs: proposal to use CTEQ6L1, for which an UE tune exists. Input Parameter Settings: all listed here: https://twiki.cern.ch/twiki/bin/view/CMS/MadgraphProduction2008Proposal Change in the pole masses to match the PDG everywhere except for W and top, where the most recent world averages are used. Note: we must take care and port these settings into other general purpose generators used in CMS Tau decays: MadGraph can handle simple tau decays correctly, do we want to use this option? Follow Tauola closely instead…

31. 31 Paolo.Bartalini@cern.chPaolo.Bartalini@cern.ch Nov 4 th ‘08 MG: Matching validation Jet rates are Jet rates are smooth at the cutoff scale independent upon the cutoff scale (under reasonable variations)