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QCD@LHC 2012

QCD@LHC 2012. Energy Dependence of the UE. Rick Field University of Florida. Outline of Talk. CDF PYTHIA 6.2 Tevatron Tune A and Tune DW. MSU August 20-23, 2012. CMS PYTHIA 6.4 LHC Tune Z1. LPCC MB&UE working group “common plots”. CDF Run 2. 300 GeV, 900 GeV, 1.96 TeV.

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QCD@LHC 2012

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  1. QCD@LHC 2012 Energy Dependence of the UE Rick Field University of Florida Outline of Talk • CDF PYTHIA 6.2 Tevatron Tune A and Tune DW. MSU August 20-23, 2012 • CMS PYTHIA 6.4 LHC Tune Z1. • LPCC MB&UE working group “common plots”. CDF Run 2 300 GeV, 900 GeV, 1.96 TeV • New UE data at 300 GeV, 900 GeV, and 1.96 TeV from the Tevatron Energy-Scan. CMS at the LHC • New comparisons with PYTHIA 6.4 Tune Z1. 900 GeV, 7 & 8 TeV • Much more coming soon! Rick Field – Florida/CDF/CMS

  2. “Hard Scattering” Component QCD Monte-Carlo Models:High Transverse Momentum Jets • Start with the perturbative 2-to-2 (or sometimes 2-to-3) parton-parton scattering and add initial and final-state gluon radiation (in the leading log approximation or modified leading log approximation). “Underlying Event” • The “underlying event” consists of the “beam-beam remnants” and from particles arising from soft or semi-soft multiple parton interactions (MPI). The “underlying event” is an unavoidable background to most collider observables and having good understand of it leads to more precise collider measurements! • Of course the outgoing colored partons fragment into hadron “jet” and inevitably “underlying event” observables receive contributions from initial and final-state radiation. Rick Field – Florida/CDF/CMS

  3. Traditional Approach CDF Run 1 Analysis • Look at charged particle correlations in the azimuthal angle Df relative to a leading object (i.e. CaloJet#1, ChgJet#1, PTmax, Z-boson). For CDF PTmin = 0.5 GeV/c hcut = 1. Charged Particle Df Correlations PT > PTmin |h| < hcut Leading Calorimeter Jet or Leading Charged Particle Jet or Leading Charged Particle or Z-Boson “Transverse” region very sensitive to the “underlying event”! • Define |Df| < 60o as “Toward”, 60o < |Df| < 120o as “Transverse”, and |Df| > 120o as “Away”. • All three regions have the same area in h-f space, Dh×Df = 2hcut×120o = 2hcut×2p/3. Construct densities by dividing by the area in h-f space. Rick Field – Florida/CDF/CMS

  4. “Transverse” Charged Density • Shows the charged particle density in the “transverse” region for charged particles (pT > 0.5 GeV/c, |h| < 1) at 7 TeVas defined by PTmax, PT(chgjet#1), and PT(muon-pair) from PYTHIATune DWat the particle level (i.e. generator level). Charged particle jets are constructed using the Anti-KT algorithm with d = 0.5. Rick Field – Florida/CDF/CMS

  5. Jet Radius Dependence The UE activity is higher for large jet radius! Tune Z1 • The charged particle density in the “transverse” region as defined by the leading charged particle jet from PYTHIA Tune Z1. The charged particles are in the region pT > 0.5 GeV/c and |h| < 2.5. Charged particle jets are constructed using the Anti-KT algorithm with d = 0.2, 0.5, and 1.0 from charged particles in the region pT > 0.5 GeV/c and |h| < 2.5, however, the leading charged particle jet is required to have |h(chgjet#1)| < 1.5. It seems that large jet radius “biases” the UE to be more active! Rick Field – Florida/CDF/CMS

  6. Tuning PYTHIA 6.2:Multiple Parton Interaction Parameters Hard Core Determines the energy dependence of the MPI! Determine by comparing with 630 GeV data! Take E0 = 1.8 TeV Reference point at 1.8 TeV Rick Field – Florida/CDF/CMS

  7. Run 1 PYTHIA Tune A CDF Default! • 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)andSet A(PARP(67)=4)). PYTHIA 6.206 CTEQ5L Run 1 Analysis 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) Rick Field – Florida/CDF/CMS

  8. “Transverse” Charged DensitiesEnergy Dependence Increasing e produces less energy dependence for the UE resulting in less UE activity at the LHC! Lowering PT0 at 630 GeV (i.e. increasing e) increases UE activity resulting in less energy dependence. • Shows the “transverse” charged PTsum density (|h|<1, PT>0.4 GeV) versus PT(charged jet#1) at 630 GeV predicted by HERWIG 6.4 (PT(hard) > 3 GeV/c, CTEQ5L) and a tuned version of PYTHIA 6.206 (PT(hard) > 0, CTEQ5L, Set A, e = 0, e = 0.16 (default) and e = 0.25 (preferred)). • Also shown are the PTsum densities (0.16 GeV/c and 0.54 GeV/c) determined from the Tano, Kovacs, Huston, and Bhatti “transverse” cone analysis at 630 GeV. Rick Field Fermilab MC Workshop October 4, 2002! Reference point E0 = 1.8 TeV Rick Field – Florida/CDF/CMS

  9. Min-Bias “Associated”Charged Particle Density • Shows the “associated” charged particle density in the “transverse” region as a function of PTmax for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmax) for “min-bias” events at 0.2 TeV, 0.9 TeV, 1.96 TeV, 7 TeV, 10 TeV, 14 TeVpredicted by PYTHIA Tune DW at the particle level (i.e. generator level). LHC14 LHC10 LHC7 Tevatron 900 GeV RHIC 0.2 TeV → 1.96 TeV (UE increase ~2.7 times) 1.96 TeV → 14 TeV (UE increase ~1.9 times) RHIC LHC Tevatron Linear scale! Rick Field – Florida/CDF/CMS

  10. Min-Bias “Associated”Charged Particle Density • Shows the “associated” charged particle density in the “transverse” region as a function of PTmax for charged particles (pT > 0.5 GeV/c, |h| < 1, not including PTmax) for “min-bias” events at 0.2 TeV, 0.9 TeV, 1.96 TeV, 7 TeV, 10 TeV, 14 TeVpredicted by PYTHIA Tune DW at the particle level (i.e. generator level). LHC14 LHC10 LHC7 Tevatron 900 GeV RHIC 7 TeV → 14 TeV (UE increase ~20%) LHC7 LHC14 Linear on a log plot! Log scale! Rick Field – Florida/CDF/CMS

  11. PYTHIA Tune DW CMS ATLAS • 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 DW at the generator level. • 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. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation. Rick Field – Florida/CDF/CMS

  12. PYTHIA Tune DW Ratio CMS CMS • Ratio of 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. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation. • 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. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation. Rick Field – Florida/CDF/CMS

  13. 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

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

  15. CMS UE Data CMS CMS Tune Z1 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 corrected and compared with PYTHIA Tune Z1 at the generator level. • 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 corrected and compared with PYTHIA Tune Z1 at the generator level. CMS corrected data! CMS corrected data! Very nice agreement! Rick Field – Florida/CDF/CMS

  16. ATLAS UE Data ATLAS ATLAS Tune Z1 Tune Z1 • ATLAS published 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 published 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. ATLAS publication – arXiv:1012.0791 December 3, 2010 Rick Field – Florida/CDF/CMS

  17. MB&UE Working Group MB & UE Common Plots CMS ATLAS • The LPCC MB&UE Working Group has suggested several MB&UE “Common Plots” the all the LHC groups can produce and compare with each other. Rick Field – Florida/CDF/CMS

  18. UE Common Plots Rick Field – Florida/CDF/CMS

  19. New CMS UE Data Less than 4% change! CMS CMS Tune Z1 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 (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. • CMS 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 generator level. CMS corrected data! CMS corrected data! Very nice agreement! Rick Field – Florida/CDF/CMS

  20. UE Common Plots Rick Field – Florida/CDF/CMS

  21. Tevatron Energy Scan • Just before the shutdown of the Tevatron CDF has collected more than 10M “min-bias” events at several center-of-mass energies! 900 GeV 300 GeV 1.96 TeV 300 GeV 12.1M MB Events 900 GeV 54.3M MB Events Rick Field – Florida/CDF/CMS

  22. New CDF UE Data 1.96 TeV 25,371,145 Events 900 GeV 37,075,521 Events • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 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| < 1.0. 300 GeV 7,233,840 Events Rick Field – Florida/CDF/CMS

  23. New CDF UE Data • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 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| < 1.0. Rick Field – Florida/CDF/CMS

  24. New CDF UE Data • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 TeV on the “transverse” charged particle average pT, as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 1.0. Rick Field – Florida/CDF/CMS

  25. Energy Dependence • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 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| < 1.0 for 5.0 < PTmax < 6.0 GeV/c. • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 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| < 1.0. Rick Field – Florida/CDF/CMS

  26. Energy Dependence • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 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| < 1.0. • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 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| < 1.0 for 5.0 < PTmax < 6.0 GeV/c. Rick Field – Florida/CDF/CMS

  27. Energy Dependence • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 TeV on the “transverse” charged particle average pT as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 1.0 for 5.0 < PTmax < 6.0 GeV/c. • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 TeV on the “transverse” charged particle average pT as defined by the leading charged particle (PTmax) for charged particles with pT > 0.5 GeV/c and |h| < 1.0. Rick Field – Florida/CDF/CMS

  28. Energy Ratio: 1960/300 • Ratio of the CDF data at 300 GeV and 1.96 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| < 1.0. Shows 1.96 TeV divided by 300 GeV. • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 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| < 1.0. Rick Field – Florida/CDF/CMS

  29. Energy Ratio: 900/300 • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 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| < 1.0. • Ratio of the CDF data at 300 GeV and 900 GeV 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| < 1.0. Shows 900 GeV divided by 300 GeV. Rick Field – Florida/CDF/CMS

  30. Energy Ratio: 1960/900 • New Corrected CDF data at 300 GeV, 900 GeV, and 1.96 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| < 1.0. • Ratio of the CDF data at 900 GeV and 1.96 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| < 1.0. Shows 1.96 TeV divided by 900 GeV. Rick Field – Florida/CDF/CMS

  31. PYTHIA 6.4 Tune Z1 ATLAS CMS CDF CDF ALICE CDF Rick Field – Florida/CDF/CMS

  32. PYTHIA 6.4 Tune Z1 CMS ATLAS CDF CDF ALICE CDF Rick Field – Florida/CDF/CMS

  33. PYTHIA 6.4 Tune Z1 Rick Field – Florida/CDF/CMS

  34. PTmax versus Leading Jet • Published CDF Run 2 data at 1.96 TeV on the “transverse” charged particle density, dN/dhdf, as defined by the leading calorimeter jet (jet#1) for charged particles with pT > 0.5 GeV/c and |h| < 1.0 compared with PYTHIA Tune Z1. • New CDF data 1.96 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| < 1.0 compared with PYTHIA Tune Z1. Okay No inconsistency But need to understand! Yikes! ??? Rick Field – Florida/CDF/CMS

  35. More Coming Soon! What we are learning should allow for a deeper understanding of MPI which will result in more precise predictions at the future LHC energy of 13 TeV! • CDF - Many More UE Observables: Nchg density, PTsum density, average pT, “toward”, “away”, “transverse”, “transMAX”, “transMIN”, distributions, etc.. • CDF - Two h Ranges: Must do (pT > 0.5 GeV/c, |h| < 0.8) as well as (pT > 0.5 GeV, |h| < 1). • CDF - Min-Bias: Many MB observables: Multiplicity, dN/dh, pT distribution, <pT> versus Nchg, etc. Soon we will have MB & UE data at 300 GeV, 900 GeV, 1.96 TeV, 7 TeV, and 8 TeV! We can study the energy dependence more precisely than ever before! Rick Field – Florida/CDF/CMS

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