MPI@LHC 2010

1. MPI@LHC 2010 New LHC Tunes: What we have learned Rick Field University of Florida Outline of Talk • The CDF Tevatron tunes do not produce enough soft particles. Glasgow, Scotland November 2010 • PYTHIA 6.4 Tune Z1: New CMS 6.4 MB tune (pT-ordered parton showers and new MPI). • Examine how well the Tune Z1 fits the LHC UE data (CMS, ATLAS, ALICE). • Examine how well Tune Z1 fits the LHC MB data (CMS,ATLAS, ALICE). Rick Field – Florida/CDF/CMS

2. PYTHIA Tune DW If one increases the pT the agreement improves! Tune DW • ALICE inelastic data at 900 GeV on the dN/dh distribution for charged particles (pT > PTmin) for events with at least one charged particle with pT > PTmin and |h| < 0.8 for PTmin = 0.15 GeV/c, 0.5 GeV/c, and 1.0 GeV/c compared with PYTHIA Tune DW at the generator level. The same thing occurs at 7 TeV! ALICE, ATLAS, and CMS data coming soon. Rick Field – Florida/CDF/CMS

3. PYTHIA Tune DW Diffraction contributes less at harder scales! Tune DW • ALICE inelastic data at 900 GeV on the dN/dh distribution for charged particles (pT > PTmin) for events with at least one charged particle with pT > PTmin and |h| < 0.8 for PTmin = 0.15 GeV/c, 0.5 GeV/c, and 1.0 GeV/c compared with PYTHIA Tune Z1 at the generator level (dashed = ND, solid = INEL). Cannot trust PYTHIA 6.2 modeling of diffraction! Rick Field – Florida/CDF/CMS

4. CMS dN/dh CMS Tune DW Soft particles! All pT • Generator level dN/dh (all pT). Shows the NSD = HC + DD and the HC = ND contributions for Tune DW. Also shows the CMS NSD data. Off by 50%! Rick Field – Florida/CDF/CMS

5. CMS dN/dh Okay if the Monte-Carlo does not fit the data what do we do? We tune the Monte-Carlo to fit the data! CMS Tune DW Soft particles! All pT • Generator level dN/dh (all pT). Shows the NSD = HC + DD and the HC = ND contributions for Tune DW. Also shows the CMS NSD data. Off by 50%! Rick Field – Florida/CDF/CMS

6. CMS dN/dh Okay if the Monte-Carlo does not fit the data what do we do? We tune the Monte-Carlo to fit the data! Be careful not to tune away new physics! CMS Tune DW Soft particles! All pT • Generator level dN/dh (all pT). Shows the NSD = HC + DD and the HC = ND contributions for Tune DW. Also shows the CMS NSD data. Off by 50%! Rick Field – Florida/CDF/CMS

7. PYTHIA Tune Z1 • All my previous tunes (A, DW, DWT, D6, D6T, CW, X1, and X2) were PYTHIA 6.4 tunes using the old Q2-ordered parton showers and the old MPI model (really 6.2 tunes)! PARP(90) PARP(82) Color • I believe that it is time to move to PYTHIA 6.4 (pT-ordered parton showers and new MPI model)! Connections Diffraction • Tune Z1: I started with the parameters of ATLAS Tune AMBT1, but I changed LO* to CTEQ5L and I varied PARP(82) and PARP(90) to get a very good fit of the CMS UE data at 900 GeV and 7 TeV. • The ATLAS Tune AMBT1 was designed to fit the inelastic data for Nchg ≥ 6 and to fit the PTmax UE data with PTmax > 10 GeV/c. Tune AMBT1 is primarily a min-bias tune, while Tune Z1 is a UE tune! UE&MB@CMS Rick Field – Florida/CDF/CMS

8. PYTHIA Tune Z1 Parameters not shown are the PYTHIA 6.4 defaults! Rick Field – Florida/CDF/CMS

9. PYTHIA Tune Z1 CMS CMS Tune Z1 • CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |h| < 2.0. The data are uncorrected and compared with PYTHIA Tune DW and D6T after detector simulation (SIM). • CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |h| < 2.0. The data are uncorrected and compared with PYTHIA Tune Z1 after detector simulation (SIM). Tune Z1 (CTEQ5L) PARP(82) = 1.932 PARP(90) = 0.275 PARP(77) = 1.016 PARP(78) = 0.538 Color reconnection suppression. Color reconnection strength. Tune Z1 is a PYTHIA 6.4 using pT-ordered parton showers and the new MPI model! Rick Field – Florida/CDF/CMS

10. PYTHIA Tune Z1 CMS CMS Tune Z1 • CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |h| < 2.0. The data are uncorrected and compared with PYTHIA Tune DW and D6T after detector simulation (SIM). • CMS preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |h| < 2.0. The data are uncorrected and compared with PYTHIA Tune Z1 after detector simulation (SIM). Tune Z1 (CTEQ5L) PARP(82) = 1.932 PARP(90) = 0.275 PARP(77) = 1.016 PARP(78) = 0.538 Color reconnection suppression. Color reconnection strength. Tune Z1 is a PYTHIA 6.4 using pT-ordered parton showers and the new MPI model! Rick Field – Florida/CDF/CMS

11. PYTHIA Tune Z1 ATLAS ATLAS Tune Z1 Tune Z1 • ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dhdf, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 2.5. The data are corrected and compared with PYTHIA Tune Z1 at the generator level. • ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dhdf, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 2.5. The data are corrected and compared with PYTHIA Tune Z1 at the generrator level. Tune Z1 (CTEQ5L) PARP(82) = 1.932 PARP(90) = 0.275 PARP(77) = 1.016 PARP(78) = 0.538 Color reconnection suppression. Color reconnection strength. Tune Z1 is a PYTHIA 6.4 using pT-ordered parton showers and the new MPI model! Rick Field – Florida/CDF/CMS

12. PYTHIA Tune Z1 ALICE ALICE Tune Z1 Tune Z1 • ALICE preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dhdf, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 0.8. The data are corrected and compared with PYTHIA Tune Z1 at the generator level. • ALICE preliminary data at 900 GeV and 7 TeV on the “transverse” charged PTsum density, dPT/dhdf, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 0.8. The data are corrected and compared with PYTHIA Tune Z1 at the generrator level. Tune Z1 (CTEQ5L) PARP(82) = 1.932 PARP(90) = 0.275 PARP(77) = 1.016 PARP(78) = 0.538 Color reconnection suppression. Color reconnection strength. Tune Z1 is a PYTHIA 6.4 using pT-ordered parton showers and the new MPI model! Rick Field – Florida/CDF/CMS

13. PYTHIA Tune Z1 ALICE ATLAS Tune Z1 Tune Z1 • ALICE preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dhdf, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 0.8. The data are corrected and compared with PYTHIA Tune Z1 at the generator level. • ATLAS preliminary data at 900 GeV and 7 TeV on the “transverse” charged particle density, dN/dhdf, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 2.5. The data are corrected and compared with PYTHIA Tune Z1 at the generrator level. Tune Z1 (CTEQ5L) PARP(82) = 1.932 PARP(90) = 0.275 PARP(77) = 1.016 PARP(78) = 0.538 Color reconnection suppression. Color reconnection strength. Tune Z1 is a PYTHIA 6.4 using pT-ordered parton showers and the new MPI model! Rick Field – Florida/CDF/CMS

14. PYTHIA Tune Z1 Tune Z1 CMS CMS • Ratio of CMS preliminary data at 900 GeV and 7 TeV (7 TeV divided by 900 GeV) on the “transverse” charged particle density as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |h| < 2.0. The data are uncorrected and compared with PYTHIA Tune DW, D6T, CW, and P0 after detector simulation (SIM). • Ratio of CMS preliminary data at 900 GeV and 7 TeV (7 TeV divided by 900 GeV) on the “transverse” charged particle density as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |h| < 2.0. The data are uncorrected and compared with PYTHIA Tune Z1 after detector simulation (SIM). Rick Field – Florida/CDF/CMS

15. PYTHIA Tune Z1 Tune Z1 CMS CMS • Ratio of CMS preliminary data at 900 GeV and 7 TeV (7 TeV divided by 900 GeV) on the “transverse” charged PTsum density as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |h| < 2.0. The data are uncorrected and compared with PYTHIA Tune DW, D6T, CW, and P0 after detector simulation (SIM). • Ratio of CMS preliminary data at 900 GeV and 7 TeV (7 TeV divided by 900 GeV) on the “transverse” charged PTsum density as defined by the leading charged particle jet (chgjet#1) for charged particles with pT > 0.5 GeV/c and |h| < 2.0. The data are uncorrected and compared with PYTHIA Tune Z1 after detector simulation (SIM). Rick Field – Florida/CDF/CMS

16. PYTHIA Tune Z1 Tune Z1 Tune Z1 ATLAS ATLAS • Ratio of the ATLAS preliminary data on the charged particle density in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2.5) at 900 GeV and 7 TeVas defined by PTmax compared with PYTHIA Tune Z1 at the generator level. • Ratio of the ATLAS preliminary data on the charged PTsum density in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2.5) at 900 GeV and 7 TeVas defined by PTmax compared with PYTHIA Tune Z1 at the generator level. Rick Field – Florida/CDF/CMS

17. PYTHIA Tune Z1 ATLAS ATLAS Tune Z1 Tune Z1 Factor of 2 increase! • ATLAS preliminary data at 7 TeV on the “transverse” charged particle density, dN/dhdf, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 2.5. The data are corrected and compared with PYTHIA Tune Z1 at the generator level. Also shows the prediction of Tune Z1 for the “transverse” charged particle density with pT > 0.1 GeV/c and |h| < 2.5. • ATLAS preliminary data at 7 TeV on the “transverse” charged PTsum density, dPT/dhdf, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 2.5. The data are corrected and compared with PYTHIA Tune Z1 at the generator level. Also shows the prediction of Tune Z1 for the “transverse” charged particle density with pT > 0.1 GeV/c and |h| < 2.5. Rick Field – Florida/CDF/CMS

18. “Transverse” Multiplicity Distribution Same hard scale at two different center-of-mass energies! CMS CMS Tune Z1 Difficult to produce enough events with large “transverse” multiplicity at low hard scale! • CMS uncorrected data at 900 GeV and 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune Z1 at the detector level (i.e. Theory + SIM). • CMS uncorrected data at 900 GeV and 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune DW and Tune D6T at the detector level (i.e. Theory + SIM). Rick Field – Florida/CDF/CMS

19. “Transverse” PTsum Distribution Same hard scale at two different center-of-mass energies! CMS CMS Tune Z1 • CMS uncorrected data at 900 GeV and 7 TeV on the charged scalar PTsum distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune DW,andTune D6T at the detector level (i.e. Theory + SIM). • CMS uncorrected data at 900 GeV and 7 TeV on the charged scalar PTsum distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune Z1,at the detector level (i.e. Theory + SIM). Difficult to produce enough events with large “transverse” PTsum at low hard scale! Rick Field – Florida/CDF/CMS

20. “Transverse” Multiplicity Distribution Same center-of-mass energy at two different hard scales! CMS CMS Tune Z1 Difficult to produce enough events with large “transverse” multiplicity at low hard scale! • CMS uncorrected data at 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune Z1 at the detector level (i.e. Theory + SIM). • CMS uncorrected data at 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune DW and Tune D6T at the detector level (i.e. Theory + SIM). Rick Field – Florida/CDF/CMS

21. “Transverse” PTsum Distribution Same center-of-mass energy at two different hard scales! CMS CMS Tune Z1 • CMS uncorrected data at 7 TeV on the charged PTsum distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune Z1 at the detector level (i.e. Theory + SIM). • CMS uncorrected data at 7 TeV on the charged PTsum distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c and PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune DW and Tune D6T at the detector level (i.e. Theory + SIM). Difficult to produce enough events with large “transverse” PTsum at low hard scale! Rick Field – Florida/CDF/CMS

22. CMS dN/dh Tune Z1 CMS CMS • Generator level dN/dh (all pT). Shows the NSD = HC + DD and the HC = ND contributions for Tune Z1. Also shows the CMS NSD data. • Generator level dN/dh (all pT). Shows the NSD = HC + DD prediction for Tune Z1 and Tune X2. Also shows the CMS NSD data. Okay not perfect, but remember we do not know if the DD is correct! Rick Field – Florida/CDF/CMS

23. PYTHIA Tune Z1 Tune Z1 • ALICE inelastic data at 900 GeV on the dN/dh distribution for charged particles (pT > PTmin) for events with at least one charged particle with pT > PTmin and |h| < 0.8 for PTmin = 0.15 GeV/c, 0.5 GeV/c, and 1.0 GeV/c compared with PYTHIA Tune DW at the generator level. Okay not perfect, but remember we do not know if the SD & DD are correct! Rick Field – Florida/CDF/CMS

24. NSD Multiplicity Distribution Difficult to produce enough events with large multiplicity! CMS Tune Z1 • Generator level charged multiplicity distribution (all pT, |h| < 2) at 900 GeV and 7 TeV. Shows the NSD = HC + DD prediction for Tune Z1. Also shows the CMS NSD data. Okay not perfect! But not that bad! Rick Field – Florida/CDF/CMS

25. NSD: <pT> versus Nchg CMS CMS Overall average pT Overall average pT • Shows the 900 GeV and 7 TeV CMS NSD corrected data on <pT> versus Nchg (all pT, |h| < 2.4) compared with Tune Z1. Okay not perfect! But not that bad! Rick Field – Florida/CDF/CMS

26. NSD: <pT> versus Nchg <pT> increases by 20% • Note that for a given multiplicity <pT> increase only very slightly with in going from 900 GeV to 7 TeV (2%-4%). However, the average pT increases by ~20% due mainly from the broadening of the multiplicity distribution! Rick Field – Florida/CDF/CMS

27. Energy Dependence Overall average pT • Shows the energy dependence of the CMS NSD corrected data on <pT> versus Nchg (all pT, |h| < 2.4) compared with Tune X2. Also shows the energy dependence of the overall <pT> compared with Tune X2. • Shows the energy dependence of the CMS NSD corrected data on <pT> versus Nchg (all pT, |h| < 2.4) compared with Tune P0, Tune PQ20, and Tune P329. It will be interesting to see if any tune can get this right! Rick Field – Florida/CDF/CMS

28. Energy Dependence Amazing! ATLAS AMBT1 probably does well here also! • Shows the energy dependence of the CMS NSD corrected data on <pT> versus Nchg (all pT, |h| < 2.4) compared with Tune Z1. Also shows the energy dependence of the overall <pT> compared with Tune Z1. First Tune (except PhoJet) to come close here! Rick Field – Florida/CDF/CMS

29. MB & UE “Min-Bias” CMS CMS Tune Z1 “Underlying Event” Tune Z1 Difficult to produce enough events with large multiplicity! • CMS uncorrected data at 900 GeV and 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 3 GeV/c compared with PYTHIA Tune Z1 at the detector level (i.e. Theory + SIM). Difficult to produce enough events with large “transverse” multiplicity at low hard scale! • Generator level charged multiplicity distribution (all pT, |h| < 2) at 900 GeV and 7 TeV. Shows the NSD = HC + DD prediction for Tune Z1. Also shows the CMS NSD data. Rick Field – Florida/CDF/CMS

30. MB & UE CMS Tune Z1 • CMS uncorrected data at 7 TeV on the charged particle multiplicity distribution in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 20 GeV/c compared with PYTHIA Tune Z1 at the detector level (i.e. Theory + SIM). Also shows the CMS corrected NSD multiplicity distribution (all pT, |h| < 2) compared with Tune Z1 at the generator. Amazing what we are asking the Monte-Carlo models to fit! Rick Field – Florida/CDF/CMS

31. Strange Particle Production • A lot more strange mesons at large pT than predicted by the Monte-Carlo Models! • K/p ratio fairly independent of the center-of-mass energy. Factor of 2! ALICE preliminary stat. error only Phojet Pythia ATLAS-CSC Pythia D6T Pythia Perugia-0 Rick Field – Florida/CDF/CMS

32. The LHC in 2011 • Beam back around 21st February. • Beam back around on February 21st! • 2 weeks re-commissioning with beam (at least). This is fun! • 4 day technical stop every 6 weeks. • 4 weeks ion run. • End of run – December 12th. • Approximately 200 days proton physics! • Maybe 8 TeV (4 TeV/beam). Rick Field – Florida/CDF/CMS