Monte-Carlo Generators for CMS CDF Run 2 CMS Outline of Talk Not favored at present! Review briefly the CDF Run 1 and Run 2 PYTHIA 6.2 tunes. UE&MB@CMS Perugia, Florida, Hamburg, Trieste Discuss four NLO structure function CTEQ6.1M PYTHIA 6.2 tunes, Tune QK and Tune QKT, Tune QW and Tune QWT. Introduce a new CTEQ6L tune Tune D6 and Tune D6T. New CTEQ6L tune! Discuss a few early measurements at CMS. FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

CDF Run 1 PYTHIA Tune A PYTHIA 6.206 CTEQ5L CDF Default! PYTHIA 6.206 CTEQ5L Parameter Tune B Tune A MSTP(81) 1 MSTP(82) 4 PARP(82) 1.9 GeV 2.0 GeV PARP(83) 0.5 PARP(84) 0.4 PARP(85) 1.0 0.9 PARP(86) 0.95 PARP(89) 1.8 TeV PARP(90) 0.25 PARP(67) 4.0 Run 1 Analysis Plot shows the “transverse” charged particle density versus PT(chgjet#1) compared to the QCD hard scattering predictions of two tuned versions of PYTHIA 6.206 (CTEQ5L, Set B (PARP(67)=1) and Set A (PARP(67)=4)). Old PYTHIA default (more initial-state radiation) Old PYTHIA default (more initial-state radiation) New PYTHIA default (less initial-state radiation) New PYTHIA default (less initial-state radiation) FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

Rick Field – Florida/CMS CDF Run 1 PT(Z) PYTHIA 6.2 CTEQ5L UE Parameters Parameter Tune A Tune A25 Tune A50 MSTP(81) 1 MSTP(82) 4 PARP(82) 2.0 GeV PARP(83) 0.5 PARP(84) 0.4 PARP(85) 0.9 PARP(86) 0.95 PARP(89) 1.8 TeV PARP(90) 0.25 PARP(67) 4.0 MSTP(91) PARP(91) 1.0 2.5 5.0 PARP(93) 15.0 25.0 ISR Parameter Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune A (<pT(Z)> = 9.7 GeV/c), Tune A25 (<pT(Z)> = 10.1 GeV/c), and Tune A50 (<pT(Z)> = 11.2 GeV/c). Vary the intrensic KT! Intrensic KT FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

CDF Run 1 PT(Z) PYTHIA 6.2 CTEQ5L Tune used by the CDF-EWK group! PYTHIA 6.2 CTEQ5L Parameter Tune A Tune AW MSTP(81) 1 MSTP(82) 4 PARP(82) 2.0 GeV PARP(83) 0.5 PARP(84) 0.4 PARP(85) 0.9 PARP(86) 0.95 PARP(89) 1.8 TeV PARP(90) 0.25 PARP(62) 1.0 1.25 PARP(64) 0.2 PARP(67) 4.0 MSTP(91) PARP(91) 2.1 PARP(93) 5.0 15.0 UE Parameters ISR Parameters Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune A (<pT(Z)> = 9.7 GeV/c), and PYTHIA Tune AW (<pT(Z)> = 11.7 GeV/c). Effective Q cut-off, below which space-like showers are not evolved. Intrensic KT The Q2 = kT2 in as for space-like showers is scaled by PARP(64)! FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

CDF Run 1 PT(Z) PYTHIA 6.2 CTEQ5L Tune used by the CDF-EWK group! PYTHIA 6.2 CTEQ5L Parameter Tune A Tune AW MSTP(81) 1 MSTP(82) 4 PARP(82) 2.0 GeV PARP(83) 0.5 PARP(84) 0.4 PARP(85) 0.9 PARP(86) 0.95 PARP(89) 1.8 TeV PARP(90) 0.25 PARP(62) 1.0 1.25 PARP(64) 0.2 PARP(67) 4.0 MSTP(91) PARP(91) 2.1 PARP(93) 5.0 15.0 UE Parameters Also fits the high pT tail! ISR Parameters Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune A (<pT(Z)> = 9.7 GeV/c), and PYTHIA Tune AW (<pT(Z)> = 11.7 GeV/c). Effective Q cut-off, below which space-like showers are not evolved. Intrensic KT The Q2 = kT2 in as for space-like showers is scaled by PARP(64)! FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

Jet-Jet Correlations (DØ) Df Jet#1-Jet#2 Jet#1-Jet#2 Df Distribution MidPoint Cone Algorithm (R = 0.7, fmerge = 0.5) L = 150 pb-1 (Phys. Rev. Lett. 94 221801 (2005)) Data/NLO agreement good. Data/HERWIG agreement good. Data/PYTHIA agreement good provided PARP(67) = 1.0→4.0 (i.e. like Tune A, best fit 2.5). FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

CDF Run 1 PT(Z) PYTHIA 6.2 CTEQ5L Parameter Tune DW Tune AW MSTP(81) 1 MSTP(82) 4 PARP(82) 1.9 GeV 2.0 GeV PARP(83) 0.5 PARP(84) 0.4 PARP(85) 1.0 0.9 PARP(86) 0.95 PARP(89) 1.8 TeV PARP(90) 0.25 PARP(62) 1.25 PARP(64) 0.2 PARP(67) 2.5 4.0 MSTP(91) PARP(91) 2.1 PARP(93) 15.0 UE Parameters ISR Parameters Shows the Run 1 Z-boson pT distribution (<pT(Z)> ≈ 11.5 GeV/c) compared with PYTHIA Tune DW, and HERWIG. Tune DW uses D0’s perfered value of PARP(67)! Intrensic KT Tune DW has a lower value of PARP(67) and slightly more MPI! FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

“Transverse” Nchg Density PYTHIA 6.2 CTEQ5L Three different amounts of MPI! UE Parameters Parameter Tune AW Tune DW Tune BW MSTP(81) 1 MSTP(82) 4 PARP(82) 2.0 GeV 1.9 GeV 1.8 GeV PARP(83) 0.5 PARP(84) 0.4 PARP(85) 0.9 1.0 PARP(86) 0.95 PARP(89) 1.8 TeV PARP(90) 0.25 PARP(62) 1.25 PARP(64) 0.2 PARP(67) 4.0 2.5 MSTP(91) PARP(91) 2/5 PARP(93) 15.0 ISR Parameter Shows the “transverse” charged particle density, dN/dhdf, versus PT(jet#1) for “leading jet” events at 1.96 TeV for PYTHIA Tune A, Tune AW, Tune DW, Tune BW, and HERWIG (without MPI). Three different amounts of ISR! Intrensic KT FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

NLO Structure Function! Tune A energy dependence! New PYTHIA 6.2 Tunes Use LO as with L = 192 MeV! Parameter Tune DW Tune D6 Tune QW Tune QK PDF CTEQ5L CTEQ6L CTEQ6.1 MSTP(2) 1 MSTP(33) PARP(31) 1.0 1.8 MSTP(81) MSTP(82) 4 PARP(82) 1.9 GeV 1.8 GeV 1.1 GeV PARP(83) 0.5 PARP(84) 0.4 PARP(85) PARP(86) PARP(89) 1.8 TeV PARP(90) 0.25 PARP(62) 1.25 PARP(64) 0.2 PARP(67) 2.5 MSTP(91) PARP(91) 2.1 PARP(93) 15.0 NLO Structure Function! K-factor (T. Sjostrand) UE Parameters Tune A energy dependence! ISR Parameter Intrinsic KT FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

NLO Structure Function! ATLAS energy dependence! New PYTHIA 6.2 Tunes Use LO as with L = 192 MeV! NLO Structure Function! Parameter Tune DWT ATLAS Tune D6T Tune QWT Tune QKT PDF CTEQ5L CTEQ6L CTEQ6.1 MSTP(2) 1 MSTP(33) PARP(31) 1.0 1.8 MSTP(81) MSTP(82) 4 PARP(82) 1.9409 GeV 1.8 GeV 1.8387 GeV 1.1237 GeV PARP(83) 0.5 PARP(84) 0.4 PARP(85) 0.33 PARP(86) 0.66 PARP(89) 1.96 TeV 1.0 TeV PARP(90) 0.16 PARP(62) 1.25 PARP(64) 0.2 PARP(67) 2.5 MSTP(91) PARP(91) 2.1 PARP(93) 15.0 5.0 K-factor (T. Sjostrand) UE Parameters ATLAS energy dependence! ISR Parameter Intrinsic KT FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

Rick Field – Florida/CMS New PYTHIA 6.2 Tunes 1.96 TeV 14 TeV PT0(MPI) GeV s(MPI) mb Tune DW 1.9409 351.7 3.1730 549.2 Tune DWT 2.6091 829.1 ATLAS 2.0046 324.5 2.7457 768.0 Tune D6 1.8387 306.3 3.0059 546.1 Tune D6T 2.5184 786.5 Tune QK 259.5 422.0 Tune QKT 588.0 Average charged particle density and PTsum density in the “transverse” region (pT > 0.5 GeV/c, |h| < 1) versus PT(jet#1) at 1.96 TeV for PY Tune DW, Tune D6, and Tune QK. FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

Rick Field – Florida/CMS New PYTHIA 6.2 Tunes 1.96 TeV 14 TeV PT0(MPI) GeV s(MPI) mb Tune DW 1.9409 351.7 3.1730 549.2 Tune DWT 2.6091 829.1 ATLAS 2.0046 324.5 2.7457 768.0 Tune D6 1.8387 306.3 3.0059 546.1 Tune D6T 2.5184 786.5 Tune QK 259.5 422.0 Tune QKT 588.0 Average charged particle density and PTsum density in the “transverse” region (pT > 0.5 GeV/c, |h| < 1) versus PT(jet#1) at 14 TeV for PY Tune DWT, Tune D6T, and Tune QKT. FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

PYTHIA 6.2 Tunes LHC Min-Bias Predictions Shows the predictions of PYTHIA Tune A, Tune DW, Tune DWT, and the ATLAS tune for the charged particle density dN/dh and dN/dY at 14 TeV (all pT). PYTHIA Tune A and Tune DW predict about 6 charged particles per unit h at h = 0, while the ATLAS tune predicts around 9. PYTHIA Tune DWT is identical to Tune DW at 1.96 TeV, but extrapolates to the LHC using the ATLAS energy dependence. FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

PYTHIA 6.2 Tunes LHC Min-Bias Predictions Shows the predictions of PYTHIA Tune A, Tune DW, Tune DWT, and the ATLAS tune for the charged particle pT distribution at 14 TeV (|h| < 1) and the average number of charged particles with pT > pTmin (|h| < 1). The ATLAS tune has many more “soft” particles than does any of the CDF Tunes. The ATLAS tune has <pT> = 548 MeV/c while Tune A has <pT> = 641 MeV/c (100 MeV/c more per particle)! FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

New PYTHIA 6.2 Tunes We now have CTEQ6L Tune D6T! 14 TeV (pT > 0.5 GeV/c, |h| < 1) <Nchg> <PTsum> (GeV/c) <PT> Tune DWT 6.268 7.091 1.131 Tune D6T 5.743 6.467 1.126 Tune QKT 5.361 6.115 0.982 Numbers for pT > 0.5 GeV/c, |h| < 1. We now have CTEQ6L Tune D6T! PseudoRapidity distribution, dN/dh, for charged particles with pT > 0.5 GeV/c at 14 TeV for PY Tune DWT, Tune D6T, and Tune QKT. Note this is “hard core” (i.e. MSEL=1, PT(hard) = 0) with no trigger and with only stable particles (i.e. MSTJ(22)=1). Tune D6T uses CTEQ6L (i.e. LHAPDF = 10042) and Tune QKT uses CTEQ6.1M (i.e. LHAPDF = 10100 or 10150 which are the same). FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

The Evolution of Charged Jets and the “Underlying Event” Charged Particle Df Correlations PT > 0.5 GeV/c |h| < 1 Look at the charged particle density in the “transverse” region! “Transverse” region very sensitive to the “underlying event”! CDF Run 1 Analysis Look at charged particle correlations in the azimuthal angle Df relative to the leading charged particle jet. Define |Df| < 60o as “Toward”, 60o < |Df| < 120o as “Transverse”, and |Df| > 120o as “Away”. All three regions have the same size in h-f space, DhxDf = 2x120o = 4p/3. FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

CDF Run 2 Min-Bias “Associated” Charged Particle Density Highest pT charged particle! “Associated” densities do not include PTmax! Use the maximum pT charged particle in the event, PTmax, to define a direction and look at the the “associated” density, dNchg/dhdf, in “min-bias” collisions (pT > 0.5 GeV/c, |h| < 1). It is more probable to find a particle accompanying PTmax than it is to find a particle in the central region! Shows the data on the Df dependence of the “associated” charged particle density, dNchg/dhdf, for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events. Also shown is the average charged particle density, dNchg/dhdf, for “min-bias” events. FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

CDF Run 2 Min-Bias “Associated” Charged Particle Density Rapid rise in the particle density in the “transverse” region as PTmax increases! PTmax > 2.0 GeV/c Transverse Region Transverse Region Ave Min-Bias 0.25 per unit h-f PTmax > 0.5 GeV/c Shows the data on the Df dependence of the “associated” charged particle density, dNchg/dhdf, for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events with PTmax > 0.5, 1.0, and 2.0 GeV/c. Shows “jet structure” in “min-bias” collisions (i.e. the “birth” of the leading two jets!). FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

CDF Run 2 Min-Bias “Associated” Charged Particle Density PY Tune A PTmax > 2.0 GeV/c Transverse Region Transverse Region PTmax > 0.5 GeV/c Shows the data on the Df dependence of the “associated” charged particle density, dNchg/dhdf, for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmax) relative to PTmax (rotated to 180o) for “min-bias” events with PTmax > 0.5 GeV/c and PTmax > 2.0 GeV/c compared with PYTHIA Tune A (after CDFSIM). PYTHIA Tune A predicts a larger correlation than is seen in the “min-bias” data (i.e. Tune A “min-bias” is a bit too “jetty”). FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

Rick Field – Florida/CMS Tune Summary Tevatron LHC PYTHIA Tune DW is very similar to Tune A except that it fits the CDF PT(Z) distribution and it uses the DØ prefered value of PARP(67) = 2.5 (determined from the dijet Df distribution). PYTHIA Tune DWT is identical to Tune DW at 1.96 TeV but uses the ATLAS energy extrapolation to the LHC (i.e. PARP(90) = 0.16). PYTHIA Tune D6 and D6T are similar to Tune DW and DWT, respectively, but use CTEQ6L (i.e. LHAPDF = 10042). PYTHIA Tune QK and QKT uses the NLO PDF CTEQ6.1M (i.e. LHAPDF = 10100 or 10150 which are the same) and use the “K-factor” to get the right amount of MPI. Not favored at present! FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS

I hope Steve Mrenna will take Next Round of Tunes? Tevatron LHC Torbjorn has made comparing tunes easy! I do not believe that we should continue to produce PYTHIA 6.2 tunes! We need one good PYTHIA 6.2 tune as a “reference tune” for the LHC (like tune DWT) to compare with early CMS data. Depending on what we see early on at CMS, we might make one new PYTHIA 6.2 tune, BUT we need to start tuning the new Monde-Carlo generators (PYTHIA 6.4, PYTHIA 8.0, Sherpa, HERWIG + JIMMY, etc.) We need to be able to easily validate the tunes within the CMS software framework. I hope Steve Mrenna will take charge of this effort! FNAL-CMS MC Generator Meeting June 7, 2007 Rick Field – Florida/CMS