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ICHEP 2012

ICHEP 2012. Energy Dependence of the UE. Rick Field University of Florida. Outline of Talk. CDF PYTHIA 6.2 Tevatron Tune DW predictions. Melbourne July 4-11, 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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ICHEP 2012

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  1. ICHEP 2012 Energy Dependence of the UE Rick Field University of Florida Outline of Talk • CDF PYTHIA 6.2 Tevatron Tune DW predictions. Melbourne July 4-11, 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 6.2 Tune DW and 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. 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

  4. 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

  5. “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

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

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

  12. 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

  13. 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

  14. 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

  15. ALICE-ATLAS UE Rick Field – Florida/CDF/CMS

  16. 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

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

  18. 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

  19. 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

  20. 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. • 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. Rick Field – Florida/CDF/CMS

  21. 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. • 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

  22. 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. • 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

  23. 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. • 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. Rick Field – Florida/CDF/CMS

  24. PYTHIA 6.2 Tune DW Rick Field – Florida/CDF/CMS

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

  26. 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

  27. More Coming Soon! What we are learning should allow for 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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