Northwest Terascale Workshop Modeling MinBias and the Underlying
Northwest Terascale Workshop Modeling Min-Bias and the Underlying Event The Underlying Event at the LHC Rick Field University of Florida Part 1 Æ Predicting the behavior of the “underlying event” at the LHC. What we expected to see. University of Oregon March 7 -11, 2011 Æ How well did we do at predicting the behavior of the “underlying event” at the LHC (900 Ge. V and 7 Te. V)? Æ PYTHIA 6. 4 Tune Z 1: CMS LHC tune (p. T-ordered parton showers and new MPI). Comparisons with the LHC UE data. CMS ATLAS UE&MB@CMS Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 1
Northwest Terascale Workshop Modeling Min-Bias and the Underlying Event Min-Bias Collisions at the LHC Rick Field University of Florida Part 2 (tomorrow) Æ How are “min-bias” collisions related to the “underlying event”. Æ How well did we do at predicting the behavior of “min- University of Oregon March 7 -11, 2011 bias” collisions at the LHC (900 Ge. V and 7 Te. V)? Æ PYTHIA 6. 4 Tune Z 1: CMS tune (p. T-ordered CMS parton showers and new MPI). Comparisons with the LHC Min-Bias data. Æ New Physics in Min-Bias? ? Observation of long-range same-side correlations at 7 Te. V. Æ Strange particle production: A problem for the models? Oregon Terascale Workshop March 7, 2011 ATLAS UE&MB@CMS Rick Field – Florida/CDF/CMS 2
Northwest Terascale Workshop Parton Showers and Event Structure at the LHC Previous Workshop February 23 -27, 2009 The last 2 years have been amazing! We now have a lot of nice LHC data on the “underlying event” and min-bias collisions. So much has happened so fast! Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 3
QCD Monte-Carlo Models: High Transverse Momentum Jets “Hard Scattering” Component “Underlying Event” Æ Start with the perturbative 2 -to-2 (or sometimes 2 -to-3) parton-parton scattering and add initial and finalstate gluon radiation (in the leading log approximation or modified leading log approximation). Æ 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“jet” an unavoidable Æ Of course the outgoing colored partons fragment into hadron and inevitably “underlying event” background to most collider observables and observables receive contributions from initial and final-state radiation. having good understand of it leads to more precise collider measurements! Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 4
QCD Monte-Carlo Models: Lepton-Pair Production “Hard Scattering” Component “Underlying Event” Æ Start with the perturbative Drell-Yan muon pair production and add initial-state gluon radiation (in the leading log approximation or modified leading log approximation). Æ The “underlying event” consists of the “beam-beam remnants” and from particles arising from soft or semi -soft multiple parton interactions (MPI). Æ Of course the outgoing colored partons fragment into hadron “jet” and inevitably “underlying event” observables receive contributions from initial-state radiation. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 5
MPI, Pile-Up, and Overlap MPI: Multiple Parton Interactions Proton Pile-Up Æ MPI: Additional 2 -to-2 parton-parton scatterings within a single hadron-hadron collision. Proton Interaction Region Dz Æ Pile-Up: More than one hadron-hadron collision in the beam crossing. Overlap Æ Overlap: An experimental timing issue where a hadron-hadron collision from the next beam crossing gets included in the hadron collision from the current beam crossing because the next crossing happened before the event could be read out. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 6
Traditional Approach CDF Run 1 Analysis Charged Particle Df Correlations PT > PTmin |h| < hcut “Transverse” region very sensitive to the “underlying event”! Leading Calorimeter Jet or Leading Charged Particle or Z-Boson Æ Look at charged particle correlations in the azimuthal angle Df relative to a leading object (i. e. Calo. Jet#1, Chg. Jet#1, PTmax, Z-boson). For CDF PTmin = 0. 5 Ge. V/c hcut = 1. Æ Define |Df| < 60 o as “Toward”, 60 o < |Df| < 120 o as “Transverse”, and |Df| > 120 o as “Away”. Æ All three regions have the same area in h-f space, Dh×Df = 2 hcut× 120 o = 2 hcut× 2 p/3. Construct densities by dividing by the area in h-f space. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 7
Transverse Charged Particle Density RDF LHC Prediction! If the LHC data are not in the range shown here then we learn new (QCD) physics! Rick Field October 13, 2009 Tevatron LHC Æ Shows the “associated” charged particle density in the “transverse” region as a function of PTmax for charged particles (p. T > 0. 5 Ge. V/c, |h| < 1, not including PTmax) for “min-bias” events at 1. 96 Te. V from PYTHIA Tune A, Tune S 320, Tune N 324, and Tune P 329 at the particle level (i. e. generator level). Æ Extrapolations of PYTHIA Tune A, Tune DWT, Tune S 320, Tune P 329, and py. ATLAS to the LHC. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 8
“Transverse” Charged Density Æ Shows the charged particle density in the “transverse” region for charged particles (p. T > 0. 5 Ge. V/c, |h| < 1) at 7 Te. V as defined by PTmax, PT(chgjet#1), and PT(muon-pair) from PYTHIA Tune DW at the particle level (i. e. generator level). Charged particle jets are constructed using the Anti-KT algorithm with d = 0. 5. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 9
Min-Bias “Associated” Charged Particle Density LHC 14 LHC 7 LHC 10 Tevatron 900 Ge. V RHIC 0. 2 Te. V → 1. 96 Te. V (UE increase ~2. 7 times) Tevatron 1. 96 Te. V → 14 Te. V (UE increase ~1. 9 times) LHC Æ Shows the “associated” charged particle density in the “transverse” region as a function of PTmax for charged particles (p. T > 0. 5 Ge. V/c, |h| < 1, not including PTmax) for “min-bias” events at 0. 2 Te. V, 0. 9 Te. V, 1. 96 Te. V, 7 Te. V, 10 Te. V, 14 Te. V predicted by PYTHIA Tune DW at the particle Linear scale! level (i. e. generator level). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 10
Min-Bias “Associated” Charged Particle Density LHC 14 LHC 10 LHC 7 Tevatron 900 Ge. V RHIC LHC 7 7 Te. V → 14 Te. V (UE increase ~20%) LHC 14 Linear on a log plot! Æ Shows the “associated” charged particle density in the “transverse” region as a function of PTmax for charged particles (p. T > 0. 5 Ge. V/c, |h| < 1, not including PTmax) for “min-bias” events at 0. 2 Te. V, 0. 9 Te. V, 1. 96 Te. V, 7 Te. V, 10 Te. V, 14 Te. V predicted by PYTHIA Tune DW at the particle Log scale! level (i. e. generator level). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 11
Conclusions November 2009 Æ We are making good progress in understanding and modeling the “underlying event”. RHIC data at 200 Ge. V are very important! Æ The new Pythia p. T ordered tunes (py 64 S 320 and py 64 P 329) are very similar to Tune A, Tune AW, and Tune DW. At present the new tunes do not fit the data better than Tune AW and Tune DW. However, the new tune are theoretically preferred! Æ It is clear now that the default value PARP(90) = 0. 16 is not correct and the value should be closer to the Tune A value of 0. 25. Æ The new and old PYTHIA tunes are beginning to converge and I believe we are finally in a position to make some legitimate predictions at the LHC! Æ All tunes with the default value PARP(90) = 0. 16 are wrong and are overestimating the activity of min-bias and the underlying event at the LHC! This includes all my “T” tunes and the (old) ATLAS tunes! Æ Need to measure “Min-Bias” and the “underlying event” at the LHC as soon as possible to see if there is new QCD physics to be learned! Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS UE&MB@CMS 12
“Transverse” Charged Particle Density Leading Charged Particle Jet, chgjet#1. Prediction! Æ Fake data (from MC) at 900 Ge. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. The fake data (from PYTHIA Tune DW) are generated at the particle level (i. e. generator level) assuming 0. 5 M min-bias events at 900 Ge. V (361, 595 events in the plot). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS Leading Charged Particle, PTmax. Rick Field MB&UE@CMS Workshop CERN, November 6, 2009 13
“Transverse” Charge Density Rick Field MB&UE@CMS Workshop CERN, November 6, 2009 factor of 2! Prediction! LHC 900 Ge. V → 7 Te. V (UE increase ~ factor of 2) ~0. 4 → ~0. 8 LHC 7 Te. V Æ Shows the charged particle density in the “transverse” region for charged particles (p. T > 0. 5 Ge. V/c, |h| < 2) at 900 Ge. V and 7 Te. V as defined by PTmax from PYTHIA Tune DW and at the particle level (i. e. generator level). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 14
“Transverse” Charged Particle Density Monte-Carlo! Real Data! Æ Fake data (from MC) at 900 Ge. V on the Æ CMS preliminary data at 900 Ge. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. The fake with p. T > 0. 5 Ge. V/c and |h| < 2. The data are data (from PYTHIA Tune DW) are uncorrected and compared with PYTHIA generated at the particle level (i. e. generator Tune DW after detector simulation (216, 215 level) assuming 0. 5 M min-bias events at 900 events in the plot). Ge. V (361, 595 events in the plot). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 15
“Transverse” Charged PTsum Density Monte-Carlo! Real Data! Æ Fake data (from MC) at 900 Ge. V on the Æ CMS preliminary data at 900 Ge. V on the “transverse” charged PTsum density, d. PT/dhdf, as defined by the leading charged particle (PTmax) and the leading charged particle jet (chgjet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. The fake data with p. T > 0. 5 Ge. V/c and |h| < 2. The data are (from PYTHIA Tune DW) are generated at uncorrected and compared with PYTHIA the particle level (i. e. generator level) Tune DW after detector simulation (216, 215 assuming 0. 5 M min-bias events at 900 Ge. V events in the plot). (361, 595 events in the plot). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 16
PYTHIA Tune DW Æ CMS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 17
PYTHIA Tune DW I read the points off with a ruler! Æ ATLAS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. 5. The data are corrected and compared with PYTHIA Tune DW at the generator level. ATLAS Note: ATLAS-CONF-2010 -029 May 29, 2010 Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 18
PYTHIA Tune DW CMS ATLAS Æ CMS preliminary data at 900 Ge. V and 7 Te. V Æ ATLAS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. 5. The data are corrected p. T > 0. 5 Ge. V/c and |h| < 2. The data are uncorrected and compared with PYTHIA Tune DW at the generator level. DW after detector simulation. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 19
PYTHIA Tune DW CMS Æ CMS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged PTsum density, d. PT/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation. Oregon Terascale Workshop March 7, 2011 ATLAS Æ ATLAS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged PTsum density, d. PT/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. 5. The data are corrected and compared with PYTHIA Tune DW at the generator level. Rick Field – Florida/CDF/CMS 20
“Transverse” Charge Density Rick Field MB&UE@CMS Workshop CERN, November 6, 2009 factor of 2! Prediction! LHC 900 Ge. V → 7 Te. V (UE increase ~ factor of 2) ~0. 4 → ~0. 8 LHC 7 Te. V Æ Shows the charged particle density in the “transverse” region for charged particles (p. T > 0. 5 Ge. V/c, |h| < 2) at 900 Ge. V and 7 Te. V as defined by PTmax from PYTHIA Tune DW and at the particle level (i. e. generator level). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 21
PYTHIA Tune DW Ratio CMS Æ CMS preliminary data at 900 Ge. V and 7 Te. V Æ Ratio of CMS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 22
PYTHIA Tune DW CMS ATLAS Æ Ratio of CMS preliminary data at 900 Ge. V Æ Ratio of the ATLAS preliminary data at and 7 Te. V on the “transverse” charged 900 Ge. V and 7 Te. V on the “transverse” particle density, d. N/dhdf, as defined by the charged particle density, d. N/dhdf, as leading charged particle jet (chgjet#1) for defined by the leading charged particles with p. T > 0. 5 Ge. V/c and |h| (PTmax) for charged particles with p. T > 0. 5 < 2. The data are uncorrected and compared Ge. V/c and |h| < 2. 5. The data are corrected with PYTHIA Tune DW after detector and compared with PYTHIA Tune DW at simulation. the generator level. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 23
PYTHIA Tune DW CMS Æ Ratio of the CMS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged PTsum density, d. PT/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. The data are uncorrected and compared with PYTHIA Tune DW after detector simulation. Oregon Terascale Workshop March 7, 2011 ATLAS Æ Ratio of the ATLAS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged PTsum density, d. PT/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. 5. The data are corrected and compared with PYTHIA Tune DW at the generator level. Rick Field – Florida/CDF/CMS 24
“Transverse” Multiplicity Distribution Same hard scale at two different center-ofmass energies! CMS Æ CMS uncorrected data at 900 Ge. V and 7 Te. V on the charged particle multiplicity distribution in the “transverse” region for charged particles (p. T > 0. 5 Ge. V/c, |h| < 2) as defined by the leading charged particle jet, chgjet#1, with PT(chgjet#1) > 3 Ge. V/c compared with PYTHIA Tune DW at the detector level (i. e. Theory + SIM). Shows the growth of the “underlying event” as the center-of-mass energy increases. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 25
“Transverse” Multiplicity Distribution Same center-of-mass energy at two different hard scales! CMS Æ CMS uncorrected data at 7 Te. V on the charged particle multiplicity distribution in the “transverse” region for charged particles (p. T > 0. 5 Ge. V/c, |h| < 2) as defined by the leading charged particle jet, chgjet#1, with PT(chgjet#1) > 3 Ge. V/c and PT(chgjet#1) > 20 Ge. V/c compared with PYTHIA Tune DW at the detector level (i. e. Theory + SIM). Shows the growth of the “underlying event” as the hard scale increases. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 26
PYTHIA Tune DW How well did we do at predicting the “underlying event” at 900 Ge. V and 7 Te. V? Tune DW ÆI am surprised that the Tunes did not do a better job of predicting the behavior of the “underlying event” at 900 Ge. V and 7 Te. V! Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS Tune DW 27
PYTHIA Tune DW How well did we do at predicting the “underlying event” at 900 Ge. V and 7 Te. V? Tune DW Warning! All the UE studies look at charged particles with p. T > 0. 5 Ge. V/c. Tune DW We do not know if the models correctly describe the UE at lower p. T values! ÆI am surprised that the Tunes did as well as they did at predicting the behavior of the “underlying event” at 900 Ge. V and 7 Te. V! Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS Tune DW 28
ATLAS Tune AMBT 1 Judith Katzy LPCC MB&UE working group meeting, May 31, 2010. Emily Nurse ICHEP, July 24, 2010. ATLAS-CONF-2010 -031 Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 29
ATLAS Tune AMBT 1 Subset of the “min-bias” data! ÆAttempt to fit a subset of the “min-bias” data (Nchg ≥ 6) where the contamination due to diffraction is expected to be small! Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 30
PYTHIA Tune Z 1 ÆAll my previous tunes (A, DWT, D 6, D 6 T, CW, X 1, and X 2) were PYTHIA 6. 4 tunes using the old Q 2 -ordered parton showers and the old MPI model (really 6. 2 tunes)! ÆI believe that it is time to move to PYTHIA 6. 4 (p. T-ordered parton showers and new MPI model)! ÆTune Z 1: I started with the parameters of ATLAS Tune AMBT 1, but I changed LO* to CTEQ 5 L and I varied PARP(82) and PARP(90) to get a very good fit of the CMS UE data at 900 Ge. V and 7 Te. V. Æ The ATLAS Tune AMBT 1 was designed to fit the inelastic data for Nchg ≥ 6 and to fit the PTmax UE data with PTmax > 10 Ge. V/c. Tune AMBT 1 is primarily a min-bias tune, while Tune Z 1 is a UE tune! Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS PARP(90) PARP(82) Color Connections Diffraction UE&MB@CMS 31
PYTHIA Tune Z 1 (R. Field CMS) Tune AMBT 1 (ATLAS) CTEQ 5 L LO* PARP(82) – MPI Cut-off 1. 932 2. 292 PARP(89) – Reference energy, E 0 1800. 0 PARP(90) – MPI Energy Extrapolation 0. 275 0. 25 PARP(77) – CR Suppression 1. 016 PARP(78) – CR Strength 0. 538 0. 1 PARP(83) – Matter fraction in core 0. 356 PARP(84) – Core of matter overlap 0. 651 PARP(62) – ISR Cut-off 1. 025 PARP(93) – primordial k. T-max 10. 0 MSTP(81) – MPI, ISR, FSR, BBR model 21 21 MSTP(82) – Double gaussion matter distribution 4 4 MSTP(91) – Gaussian primordial k. T 1 1 MSTP(95) – strategy for color reconnection 6 6 Parameter Parton Distribution Function Parameters not shown are the PYTHIA 6. 4 defaults! PARP(80) – Probability colored parton from BBR Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 32
CMS UE Data CMS Tune Z 1 Æ CMS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. 0. The data are uncorrected and compared with PYTHIA Tune DW and D 6 T after detector simulation Tune Z 1 after detector simulation (SIM). Color reconnection suppression. Color reconnection strength. Oregon Terascale Workshop March 7, 2011 Tune Z 1 (CTEQ 5 L) PARP(82) = 1. 932 PARP(90) = 0. 275 PARP(77) = 1. 016 PARP(78) = 0. 538 Rick Field – Florida/CDF/CMS Tune Z 1 is a PYTHIA 6. 4 using p. T-ordered parton showers and the new MPI model! 33
CMS UE Data CMS Tune Z 1 Æ CMS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged PTsum density, d. PT/dhdf, as defined by the leading charged particle jet (chgjet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. 0. The data are uncorrected and compared with PYTHIA Tune DW and D 6 T after detector simulation Tune Z 1 after detector simulation (SIM). Color reconnection suppression. Color reconnection strength. Oregon Terascale Workshop March 7, 2011 Tune Z 1 (CTEQ 5 L) PARP(82) = 1. 932 PARP(90) = 0. 275 PARP(77) = 1. 016 PARP(78) = 0. 538 Rick Field – Florida/CDF/CMS Tune Z 1 is a PYTHIA 6. 4 using p. T-ordered parton showers and the new MPI model! 34
ATLAS UE Data ATLAS Tune Z 1 Æ ATLAS published data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. 5. The data are corrected and compared with PYTHIA Tune Z 1 at the generator level. I read the points off with a ruler! ATLAS Æ ATLAS published data at 900 Ge. V and 7 Te. V on the “transverse” charged PTsum density, d. PT/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. 5. The data are corrected and compared with PYTHIA Tune Z 1 at the generrator level. ATLAS publication – ar. Xiv: 1012. 0791 December 3, 2010 Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 35
PYTHIA Tune Z 1 ATLAS Tune Z 1 Factor of 2 increase! Æ ATLAS preliminary data at 7 Te. V on the “transverse” charged particle density, “transverse” charged PTsum density, d. N/dhdf, as defined by the leading charged d. PT/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. 5. The data are corrected and compared with PYTHIA Tune Z 1 at the generator level. Also shows the prediction of Tune Z 1 for the “transverse” charged particle density with p. T > 0. 1 Ge. V/c Rick Field and |h| < 2. 5. MPI@LHC 2010 Glasgow, Scotland December 2, 2010 Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 36
ATLAS UE Data Tune Z 1 Æ ATLAS published data at 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and p. T > 0. 1 Ge. V/c (|h| < 2. 5). The data are corrected and compared with PYTHIA Tune Z 1 at the generator level. I read the points off with a ruler! ATLAS Æ ATLAS published data at 7 Te. V on the “transverse” charged PTsum density, d. PT/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and p. T > 0. 1 Ge. V/c (|h| < 2. 5). The data are corrected and compared with PYTHIA Tune Z 1 at the generator level. ATLAS publication – ar. Xiv: 1012. 0791 December 3, 2010 Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 37
ALICE UE Data Tune Z 1 ALICE Æ ALICE preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected and compared with PYTHIA Tune Z 1 at the generator level. I read the points off with a ruler! Oregon Terascale Workshop March 7, 2011 Tune Z 1 ALICE Æ ALICE preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged PTsum density, d. PT/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected and compared with PYTHIA Tune Z 1 at the generrator level. ALICE UE Data: Talk by S. Vallero MPI@LHC 2010 Glasgow, Scotland November 30, 2010 Rick Field – Florida/CDF/CMS 38
ATLAS UE Data ATLAS Tune Z 1 Æ ATLAS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected and compared with PYTHIA Tune Z 1 at the generator level. I read the points off with a ruler! Oregon Terascale Workshop March 7, 2011 Æ ATLAS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged PTsum density, d. PT/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected and compared with PYTHIA Tune Z 1 at the generrator level. ATLAS-CONF-2011 -009 February 21, 2011 Rick Field – Florida/CDF/CMS 39
ATLAS UE Data Tune Z 1 ATLAS Æ ATLAS preliminary data at 7 Te. V on the “transverse” charged PTsum density, “transverse” charged particle density, d. PT/dhdf, as defined by the leading charged d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8 and |h| < 2. 5. The data are corrected and compared with PYTHIA Tune Z 1 at the generrator level. PYTHIA Tune Z 1 at the generator level. I read the points off with a ruler! Oregon Terascale Workshop March 7, 2011 ATLAS-CONF-2011 -009 February 21, 2011 Rick Field – Florida/CDF/CMS 40
ATLAS UE Data ATLAS Tune Z 1 Æ ATLAS preliminary data at 900 Ge. V on the “transverse” charged PTsum density, “transverse” charged particle density, d. PT/dhdf, as defined by the leading charged d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8 and |h| < 2. 5. The data are corrected and compared with PYTHIA Tune Z 1 at the generrator level. PYTHIA Tune Z 1 at the generator level. I read the points off with a ruler! Oregon Terascale Workshop March 7, 2011 ATLAS-CONF-2011 -009 February 21, 2011 Rick Field – Florida/CDF/CMS 41
ALICE-ATLAS UE Tune Z 1 ALICE Tune Z 1 Æ ALICE preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected and compared with PYTHIA Tune Z 1 at the generator level. Oregon Terascale Workshop March 7, 2011 ATLAS Æ ATLAS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected and compared with PYTHIA Tune Z 1 at the generrator level. Rick Field – Florida/CDF/CMS 42
ALICE-ATLAS UE Tune Z 1 ALICE Tune Z 1 Æ ALICE preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected and compared with PYTHIA Tune Z 1 at the generator level. Oregon Terascale Workshop March 7, 2011 ATLAS Æ ATLAS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged particle (PTmax) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 0. 8. The data are corrected and compared with PYTHIA Tune Z 1 at the generrator level. Rick Field – Florida/CDF/CMS 43
PYTHIA Tune Z 1 CMS CDF Æ CMS preliminary data at 900 Ge. V and 7 Te. V Æ CDF published data at 1. 96 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged d. N/dhdf, as defined by the leading particle jet (chgjet#1) for charged particles calorimeter jet (jet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. The data are with p. T > 0. 5 Ge. V/c and |h| < 1. 0. The data uncorrected and compared with PYTHIA are corrected and compared with PYTHIA Tune Z 1 after detector simulation. Tune Z 1 at the generator level. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 44
PYTHIA Tune Z 1 Oops Tune Z 1 is slightly high at CDF! Tune Z 1 CMS CDF Æ CMS preliminary data at 900 Ge. V and 7 Te. V Æ CDF published data at 1. 96 Te. V on the “transverse” charged particle density, d. N/dhdf, as defined by the leading charged d. N/dhdf, as defined by the leading particle jet (chgjet#1) for charged particles calorimeter jet (jet#1) for charged particles with p. T > 0. 5 Ge. V/c and |h| < 2. The data are with p. T > 0. 5 Ge. V/c and |h| < 1. 0. The data uncorrected and compared with PYTHIA are corrected and compared with PYTHIA Tune Z 1 after detector simulation. Tune Z 1 at the generator level. Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 45
PYTHIA Tune Z 1 p. T 0(W)=p. T 0(W/W 0)e Æ MPI Cut-Off versus the Center-of Mass Energy Wcm: PYTHIA Tune Z 1 was determined by fitting p. T 0 independently at 900 Ge. V and 7 Te. V and calculating e = PARP(90). The best fit to p. T 0 at CDF is slightly higher than the Tune Z 1 curve. This is very preliminary! Perhaps with a global fit to all three energies (i. e. “Professor” tune) one can get a simultaneous fit to all three? ? p. T 0(W)=p. T 0(W/W 0)e e = PARP(90) p. T 0 = PARP(82) W = Ecm Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 46
PYTHIA Tune Z 1 More UE activity for W > 7 Te. V!? ? Æ MPI Cut-Off versus the Center-of Mass Energy Wcm: PYTHIA Tune Z 1 was determined by fitting p. T 0 independently at 900 Ge. V and 7 Te. V and calculating e = PARP(90). The best fit to p. T 0 at CDF is slightly higher than the Tune Z 1 curve. This is very preliminary! Perhaps with a global fit to all three energies (i. e. “Professor” tune) one can get a simultaneous fit to all three? ? p. T 0(W)=p. T 0(W/W 0)e e = PARP(90) p. T 0 = PARP(82) W = Ecm Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 47
“Transverse” Multiplicity Distribution Same hard scale at two different center-ofmass energies! CMS Tune Z 1 Difficult to produce Æ CMS uncorrected data at 900 Ge. V and 7 Te. V on Æ CMS uncorrected data at 900 Ge. V and 7 enough events with Te. V on the charged particle multiplicity distribution in large “transverse” the “transverse” region for charged particles (p. T > distribution in the “transverse” region multiplicity low. Ge. V/c, |h| for charged particles (p. T at > 0. 5 Ge. V/c, |h| < 2) as defined by the leading hard < 2) as defined by the scale! leading charged particle jet with PT(chgjet#1) > 3 Ge. V/c compared with PYTHIA Tune DW and Tune D 6 T particle jet with PT(chgjet#1) > 3 Ge. V/c compared with PYTHIA Tune Z 1 at the detector level (i. e. Theory + SIM). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 48
“Transverse” PTsum Distribution Same hard scale at two different center-ofmass energies! CMS Tune Z 1 Æ CMS uncorrected data at 900 Ge. V and 7 Te. V Difficult to produce on the charged scalar PTsum distribution in enough events with the “transverse” region for charged particles large “transverse” (p. T > 0. 5 Ge. V/c, |h| < 2) as defined by the PTsum leading charged particle jet with PT(chgjet#1) leading charged particleat jetlow with PT(chgjet#1) hard scale! > 3 Ge. V/c compared with PYTHIA Tune Z 1, DW, and Tune D 6 T at the detector level (i. e. Theory + SIM). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 49
“Transverse” Multiplicity Distribution CMS Same center-of-mass energy at two different hard scales! CMS Tune Z 1 Difficult Æ CMS uncorrected datatoatproduce 7 Te. V on the Æ CMS uncorrected data at 7 Te. V on the enough events with charged particle multiplicity distribution in large “transverse” region for charged particles the “transverse” multiplicity low by the (p. T > 0. 5 Ge. V/c, |h| < 2) as at defined (p. T > 0. 5 Ge. V/c, |h| < 2) as defined by the hard scale! jet with PT(chgjet#1) leading charged particle > 3 Ge. V/c and PT(chgjet#1) > 20 Ge. V/c compared with PYTHIA Tune DW and Tune compared with PYTHIA Tune Z 1 at the D 6 T at the detector level (i. e. Theory + SIM). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 50
“Transverse” PTsum Distribution Same center-of-mass energy at two different hard scales! CMS Tune Z 1 Æ CMS uncorrected data at 7 Te. V on the charged Difficultintothe produce PTsum distribution “transverse” region for PTsum distribution in the “transverse” region enough events with |h| < 2) as for charged particles (p. T > 0. 5 Ge. V/c, |h| < 2) as charged particles (p. T > 0. 5 Ge. V/c, “transverse” defined by thelarge leading charged particle jet with defined by the leading charged particle jet with PTsum low. PT(chgjet#1) > 20 PT(chgjet#1) > 3 Ge. V/catand PT(chgjet#1) > 3 Ge. V/c and PT(chgjet#1) > 20 Ge. V/c comparedhard with scale! PYTHIA Tune Z 1 at the Ge. V/c compared with PYTHIA Tune DW and detector level (i. e. Theory + SIM). Tune D 6 T at the detector level (i. e. Theory + SIM). Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 51
NSD Multiplicity Distribution CMS Difficult to produce enough events with large multiplicity! Tune Z 1 Æ Generator level charged multiplicity distribution (all p. T, |h| < 2) at 900 Ge. V and 7 Te. V. Shows the NSD = HC + DD prediction for Tune Z 1. Also shows the CMS NSD data. Okay not perfect! But not that bad! Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 52
MB & UE “Min-Bias” CMS Tune Z 1 “Underlying Event” Tune Z 1 Difficult to produce enough events with large multiplicity! Æ Generator level charged multiplicity distribution (all p. T, |h| < 2) at 900 Ge. V and 7 Te. V. Shows the NSD = HC + DD prediction for Tune Z 1. Also shows the CMS NSD data. Oregon Terascale Workshop March 7, 2011 Æ CMS uncorrected Difficult datatoatproduce 900 Ge. V and 7 Te. V on the charged enoughparticle events with multiplicity distribution inlarge the “transverse”region for charged particles multiplicity (p. T >at 0. 5 low Ge. V/c, |h| < 2) as defined byhard the leading scale! charged particle jet with PT(chgjet#1) > 3 Ge. V/c compared with PYTHIA Tune Z 1 at the detector level (i. e. Theory + SIM). Rick Field – Florida/CDF/CMS 53
MB & UE CMS Tune Z 1 Æ CMS uncorrected data at 7 Te. V on the charged particle multiplicity distribution in the “transverse” region for charged particles (p. T > 0. 5 Ge. V/c, |h| < 2) as defined by the leading charged particle jet with PT(chgjet#1) > 20 Ge. V/c compared with PYTHIA Tune Z 1 at the detector level (i. e. Theory + SIM). Also shows the CMS corrected NSD multiplicity distribution (all p. T, |h| < 2) compared with Tune Z 1 at the generator. Amazing what we are asking the Monte-Carlo models to fit! Oregon Terascale Workshop March 7, 2011 Rick Field – Florida/CDF/CMS 54
Summary & Conclusions ÆI am surprised that the Tunes did as well as they did at predicting the behavior of the “underlying event” at 900 Ge. V and 7 Te. V! Remember this is “soft” QCD! ÆTune Z 1 does nice fob of fitting the CMS, ATLAS, and ALICE UE data at 900 Ge. V and 7 Te. V! But Tune Z 1 is a little high at CDF (1. 96 Te. V)! Not bad on MB! I still dream of a “universal” tune that fits the UE at all energies! Need to simultaneously tune LHC plus CDF (“professor” tune)! ÆSurprises: more soft particles than expected!, high multiplicity tails (possible new source of “soft” events with high multiplicity? ), strange particles and baryons in the UE? ? ÆNext Step: More PYTHIA 6. 4 and PYTHIA 8 tunes. Time to look more closely at Sherpa and HERWIG++! Oregon Terascale Workshop March 7, 2011 CMS UE paper with corrected data using charged particle jets to appear next week! Rick Field – Florida/CDF/CMS 55
Northwest Terascale Workshop Modeling Min-Bias and the Underlying Event Min-Bias Collisions at the LHC Rick Field University of Florida Part 2 (tomorrow) Æ How are “min-bias” collisions related to the “underlying event”. Æ How well did we do at predicting the behavior of “min- University of Oregon March 7 -11, 2011 bias” collisions at the LHC (900 Ge. V and 7 Te. V)? Æ PYTHIA 6. 4 Tune Z 1: CMS tune (p. T-ordered CMS parton showers and new MPI). Comparisons with the LHC Min-Bias data. Æ New Physics in Min-Bias? ? Observation of long-range same-side correlations at 7 Te. V. Æ Strange particle production: A problem for the models? Oregon Terascale Workshop March 7, 2011 ATLAS UE&MB@CMS Rick Field – Florida/CDF/CMS 56
- Slides: 56