Boost 2011 May 22 26 2011 The Underlying
Boost 2011 May 22 -26, 2011 The Underlying Event & Fragmentation Tuning Rick Field University of Florida Outline Æ LHC PYTHIA Tunes: PYTHIA 6. 4 tunes (AMBT 1, Z 2) and PYTHIA 8 Tune C 4. Æ CMS-ATLAS-ALICE (corrected) UE data at (900 Ge. V and 7 CMS Te. V) and comparisons with the LHC tunes. Æ Baryon and Strange Particle Production at the LHC: Fragmentation tuning. ATLAS UE&MB@CMS Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 1
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! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 2
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. Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 3
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 Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 4
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! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 5
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! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS PARP(90) PARP(82) Color Connections Diffraction UE&MB@CMS 6
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 Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 7
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. Boost 2011, Princeton, NJ May 23, 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! 8
PYTHIA 6. 2 Tunes UE Parameters ISR Parameter Tune AW Tune D 6 PDF CTEQ 5 L CTEQ 6 L MSTP(81) 1 1 1 MSTP(82) 4 4 4 PARP(82) 2. 0 Ge. V 1. 9 Ge. V 1. 8 Ge. V PARP(83) 0. 5 PARP(84) 0. 4 PARP(85) 0. 9 1. 0 PARP(86) 0. 95 1. 0 PARP(89) 1. 8 Te. V PARP(90) 0. 25 PARP(62) 1. 25 PARP(64) 0. 2 PARP(67) 4. 0 2. 5 MSTP(91) 1 1 1 PARP(91) 2. 1 PARP(93) 15. 0 Uses CTEQ 6 L Reduce PARP(82) by factor of 1. 8/1. 9 = 0. 95 Everything else the same! Tune A energy dependence! (not the default) Intrinsic KT CMS: We wanted a CTEQ 6 L version of Tune Z 1 in a hurry! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 9
PYTHIA Tune Z 2 My guess! Tune Z 1 (R. Field CMS) Tune Z 2 (R. Field CMS) CTEQ 5 L CTEQ 6 L PARP(82) – MPI Cut-off 1. 932 1. 832 PARP(89) – Reference energy, E 0 1800. 0 PARP(90) – MPI Energy Extrapolation 0. 275 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 PARP(80) – Probability colored parton from BBR Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS Reduce PARP(82) by factor of 1. 83/1. 93 = 0. 95 Everything else the same! 10
PYTHIA Tune Z 2 My guess! Tune Z 1 (R. Field CMS) Tune Z 2 (R. Field CMS) CTEQ 5 L CTEQ 6 L PARP(82) – MPI Cut-off 1. 932 1. 832 PARP(89) – Reference energy, E 0 1800. 0 PARP(90) – MPI Energy Extrapolation 0. 275 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 PARP(80) – Probability colored parton from BBR Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS Reduce PARP(82) by factor of 1. 83/1. 93 = 0. 95 Everything else the same! PARP(90) same For Z 1 and Z 2! 11
PYTHIA 8 Tunes R. Corke and T. Sjöstrand CTEQ 6 L MRST LO** CTEQ 6 L PT 0 = PARP(82) e = PARP(90) Tevatron LHC p. T 0(W)=p. T 0(W/W 0)e e = PARP(90) p. T 0 = PARP(82) W = Ecm Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 12
PYTHIA Tune Z 2 (R. Field CMS) PY 8 Tune C 4 (Corke-Sjöstrand) CTEQ 6 L PARP(82) – MPI Cut-off 1. 832 2. 085 PARP(89) – Reference energy, E 0 1800. 0 PARP(90) – MPI Energy Extrapolation 0. 275 0. 19 PARP(77) – CR Suppression 1. 016 PARP(78) – CR Strength 0. 538 Parameter Parton Distribution Function PARP(80) – Probability colored parton from BBR 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 MSTP(82) – Double gaussion matter distribution 4 MSTP(91) – Gaussian primordial k. T 1 MSTP(95) – strategy for color reconnection 6 Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS PARP(90) much different! 13
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, on the “transverse” charged particle density, d. PT/dhdf, as defined by the leading charged 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 corrected and compared with PYTHIA Tune Z 1 at the generator level. CMS corrected data! Boost 2011, Princeton, NJ May 23, 2011 Very nice agreement! Rick Field – Florida/CDF/CMS corrected data! 14
PYTHIA 6. 4 Tune Z 2 Æ CMS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged PTsum density, on the “transverse” charged particle density, d. PT/dhdf, as defined by the leading charged 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 corrected and compared with PYTHIA Tune Z 2 at the generator level. CMS corrected data! Boost 2011, Princeton, NJ May 23, 2011 Not good! Bad energy dependence! Rick Field – Florida/CDF/CMS corrected data! 15
PYTHIA 8 Tune C 4 PY 8 Tune C 4 Æ CMS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” charged PTsum density, on the “transverse” charged particle density, d. PT/dhdf, as defined by the leading charged 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 corrected and compared with PYTHIA 8 Tune C 4 at the generator level. CMS corrected data! Boost 2011, Princeton, NJ May 23, 2011 Not good! PTsum too small! Rick Field – Florida/CDF/CMS corrected data! 16
Transverse Ratio: PTsum/Nchg Tune Z 2 Tune Z 1 Æ CMS preliminary data at 900 Ge. V and 7 Te. V on the “transverse” ratio PTsum/Nchg 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 compared with PYTHIA Tune Z 1, Z 2, and PY 8 C 4 at the generator level. PY 8 Tune C 4 Z 1 good! PY 8 C 4 and Z 2 Bad! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 17
Energy Dependence CTEQ 6 L: PARP(90) = 0. 19 CTEQ 6 L: PARP(90) =0. 275 CTEQ 5 L: PARP(90) =0. 275 Æ CMS data on the energy dependence (7 Te. V divided by 900 Ge. V) of the “transverse” charged particle density 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 compared with PYTHIA Tune Z 1, Z 2, and PY 8 C 4 at the generator level. CMS corrected data! Boost 2011, Princeton, NJ May 23, 2011 Æ CMS data on the energy dependence (7 Te. V divided by 900 Ge. V) of the “transverse” charged PTsum density 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 compared with PYTHIA Tune Z 1, Z 2, and PY 8 C 4 at the generator level. Duh! The energy dependence depends on Z 1 and PY 8 C 4 good! Z 2 Bad! both PARP(90) and the structure function! Rick Field – Florida/CDF/CMS corrected data! 18
PYTHIA Tune Z 2* Tune Z 2 (R. Field CMS) Tune Z 2* (CMS) PY 8 Tune C 4 (Corke-Sjöstrand) CTEQ 6 L PARP(82) – MPI Cut-off 1. 832 1. 927 2. 085 PARP(89) – Reference energy, E 0 1800. 0 PARP(90) – MPI Energy Extrapolation 0. 275 0. 225 0. 19 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 PARP(80) – Probability colored parton from BBR Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS GEN Group: Working on an improved Z 2 tune (Tune Z 2*) using the Professor (A. Knutsson & M. Zakaria). 19
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. 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 Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 20
CMS-ATLAS UE Data CMS: Chgjet#1 ATLAS: PTmax Tune Z 1 Æ CMS preliminary data at 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 together with the 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 |h| < 2. 5 The data are corrected and compared with PYTHIA Tune Z 1 at the generator level. Amazing agreement! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 21
ATLAS UE Data Tune Z 1 ATLAS 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. 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 Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 22
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! Boost 2011, Princeton, NJ May 23, 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 23
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. Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 24
UE Summary & Conclusions ÆWe now have lots of corrected UE data from the LHC! Tune Z 1 (CTEQ 5 L) does nice job 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)! I still dream of a “universal” tune that fits the UE at all energies! Need to simultaneously tune LHC plus CDF (“professor” tune)! ÆCTEQ 6 L Tune: PYTHIA 6. 4 Tune Z 2 and PYTHIA 8 Tune C 4 both use CTEQ 6 L, but do not fit the LHC UE data as well as Tune Z 1. ÆNext Step: More PYTHIA 6. 4 and PYTHIA 8 tunes. to look more CMSTime GEN Group: Working on an improved tune (Tune Z 2*) and an closely at Sherpa and. Z 2 HERWIG++! improved PY 8 C 4 tune (Tune C 4*) using the Professor (A. Knutsson & M. Zakaria). Sorry not enough time to show all the LHC tunes! ÆATLAS Tuning Effort (A. Buckley, J. Katzy et al. ): AMBT 1, AUET 1 (Herwig+Jimmy). Coming soon AUET 2 (Herwig + Jimmy), AMBT 2! Four stage approach: Flavor, FS fragmentation, ISR, MPI. Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 25
Min-Bias Collisions INEL = NSD + SD ALICE NSD = ND + DD CMS Tune Z 1 Æ CMS NSD data on the charged particle rapidity distribution at 7 Te. V compared with PYTHIA Tune Z 1. The plot shows the average number of particles per NSD collision per unit h, (1/NNSD) d. N/dh. Æ ALICE NSD data on the charged particle rapidity distribution at 900 Ge. V compared with PYTHIA Tune Z 1. The plot shows the average number of particles per INEL collision per unit h, (1/NINEL) d. N/dh. Okay not perfect, but remember we know that SD and DD are not modeled well! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 26
Baryon & Strange Particle Production at the LHC Æ Strange Particle Production in Proton-Proton Collisions at 900 Ge. V with ALICE at the LHC, ar. Xiv: 1012. 3257 [hep-ex] December 18, 2010. INEL Æ Production of Pions, Kaons and Protons in pp Collisions at 900 Ge. V with ALICE at the LHC, ar. Xiv: 1101. 4110 [hep-ex] January 25, 2011. Æ Strange Particle Production in pp Collisions at 900 Ge. V and 7 Te. V, CMS Paper: ar. Xiv: 1102. 4282 [hep-ex] Feb 21, 2011, submitted to JHEP. Step 1: Look at the overall particle yields (all p. T). INEL NSD I know there are more nice results from the LHC, but this is all I can show today. Sorry! Step 2: Look at the ratios of the overall particle yields (all p. T). Step 3: Look at the p. T dependence of the particle yields and ratios. Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 27
Kaon Production CMS INEL = NSD + SD Tune Z 1 Æ CMS NSD data on the Kshort rapidity distribution at 7 Te. V and 900 Ge. V distribution at 900 Ge. V and the ALICE point compared with PYTHIA Tune Z 1. The plot at Y = 0 (INEL) compared with PYTHIA shows the average number of Kshort per NSD Tune Z 1. The ALICE point is the average collision per unit Y, (1/NNSD) d. N/d. Y. number of Kshort per INEL collision per unit Y at Y = 0, (1/NINEL) d. N/d. Y. No overall shortage of Kaons in PYTHIA Tune Z 1! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 28
Kaon Production ALICE Tune Z 1 Æ ALICE INEL data on the charged kaon rapidity distribution at 900 Ge. V compared with PYTHIA Tune Z 1. The plot shows the average number of charged kaons per INEL collision per unit Y at Y = 0, (1/NINEL) d. N/d. Y. Æ ALICE INEL data on the charged kaon to charged pion rapidity ratio at 900 Ge. V compared with PYTHIA Tune Z 1. No overall shortage of Kaons in PYTHIA Tune Z 1! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 29
Kaon Production CMS measures (1/NNSD) d. N/d. Y I have plotted the same data twice! This is the correct way! versus |Y| from 0 → 2 Æ Rick’s plot of the CMS NSD data on the Kshort Æ Real CMS NSD data on the Kshort rapidity distribution at 7 Te. V and 900 Ge. V. The plot shows the average number of Kshort per NSD collision per unit Y, (1/NNSD) d. N/d. Y, versus Y from -2 → 2. |Y| from 0 → 2. Warning: I am not plotting what CMS actually measures! I am old and I like to see both sides so I assumed symmetry about Y = 0 and plotted the same data on both sides (Y → -Y). The way CMS does it is the correct way! But my way helps me see better what is going on. Please refer to the CMS publication for the official plots! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 30
Lambda Production CMS Factor of 1. 5! CMS Tune Z 1 Æ CMS NSD data on the Lambda+Anti. Lambda to rapidity distribution at 7 Te. V and 900 Ge. V 2 Kshort rapidity ratio at 7 Te. V compared with PYTHIA Tune Z 1. The plot PYTHIA Tune Z 1. shows the average number of particles per NSD collision per unit Y, (1/NNSD) d. N/d. Y. Oops! Not enough Lambda’s in PYTHIA Tune Z 1! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 31
Cascade Production CMS Factor of 2! Tune Z 1 Æ CMS NSD data on the Cascade-+Anti. Cascade- Æ CMS data on the Cascade-+Anti. Cascade- to rapidity distribution at 7 Te. V and 900 Ge. V 2 Kshort rapidity ratio at 7 Te. V compared with PYTHIA Tune Z 1. The plot PYTHIA Tune Z 1. shows the average number of particles per NSD collision per unit Y, (1/NNSD) d. N/d. Y. Yikes! Way too few Cascade’s in PYTHIA Tune Z 1! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 32
PYTHIA Fragmentation Parameters Can we increase the overall rate of strange baryons without messing up anything else? Æ PARJ(1) : (D = 0. 10) is P(qq)/P(q), the suppression of diquark-antidiquark pair production in the colour field, compared with quark–antiquark production. Notation: PARJ(1) = qq/q Æ PARJ(2) : (D = 0. 30) is P(s)/P(u), the suppression of s quark pair production in the field compared with u or d pair production. Notation: PARJ(2) = s/u. Æ PARJ(3) : (D = 0. 4) is (P(us)/P(ud))/(P(s)/P(u)), the extra suppression of strange diquark production compared with the normal suppression of strange quarks. Notation: PARJ(3) = us/u. Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 33
PYTHIA Fragmentation Parameters Æ PYTHIA Tune Z 1 C: Same as Tune Z 1 except qq/q is increased 0. 1 → 0. 12 and us/s is increased from 0. 4 → 0. 8. Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 34
Kaon Production CMS Tune Z 1 C Æ CMS d. NSD ata on the Kshort rapidity Æ CMS NSD data on the Kshort rapidity distribution at 7 Te. V and 900 Ge. V compared with PYTHIA Tune Z 1 C. The plot shows the with PYTHIA Tune Z 1. The plot shows the average number of Kshort per NSD collision per unit Y, (1/NNSD) d. N/d. Y. For Kaon production Tune Z 1 and Z 1 C are almost identical! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 35
Lambda Production CMS Tune Z 1 C Tune Z 1 Æ CMS NSD data on the Lambda+Anti. Lambda rapidity distribution at 7 Te. V and 900 Ge. V compared with PYTHIA Tune Z 1. The plot shows the average number of particles per NSD collision per unit Y, (1/NNSD) d. N/d. Y. Not bad! Many more Lambda’s in PYTHIA Tune Z 1 C! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 36
Cascade Production CMS Tune Z 1 C Tune Z 1 Æ CMS NSD data on the Cascade-+Anti. Cascaderapidity distribution at 7 Te. V and 900 Ge. V compared with PYTHIA Tune Z 1. The plot shows the average number of particles per NSD collision per unit Y, (1/NNSD) d. N/d. Y. Wow! PYTHIA Tune Z 1 C looks very nice here! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 37
Transverse Momentum Distributions Æ CMS NSD data on the Kshort transverse momentum distribution at 7 Te. V compared with PYTHIA Tune Z 1 & Z 1 C. The plot shows the average number of particles per NSD collision per unit p. T, (1/NNSD) d. N/dp. T for |Y| < 2. Æ CMS NSD data on the Lambda+Anti. Lambda transverse momentum distribution at 7 Te. V compared with PYTHIA Tune Z 1 & Z 1 C. The plot shows the average number of particles per NSD collision per unit p. T, (1/NNSD) d. N/dp. T for |Y| < 2. PYTHIA Tune Z 1 & Z 1 C are a bit off on the p. T dependence! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 38
Transverse Momentum Distributions Æ CMS NSD data on the Cascade-+Anti. Cascade- Æ CMS NSD data on the Cascade-+Anti. Cascadetransverse momentum distribution at 7 Te. V compared with PYTHIA Tune Z 1 & Z 1 C. The (normalized to 1) compared with PYTHIA plot shows the average number of particles per Tune Z 1 & Z 1 C. NSD collision per unit p. T, (1/NNSD) d. N/dp. T for |Y| < 2. PYTHIA Tune Z 1 & Z 1 C are a bit off on the p. T dependence! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 39
Particle Ratios versus PT Æ CMS NSD data on the Lambda+Anti. Lambda Æ ALICE INEL data on the Lambda+Anti. Lambda to 2 Kshort ratio versus p. T at 7 Te. V (|Y| < 2) to 2 Kshort ratio versus p. T at 900 Ge. V (|Y| < 0. 75) compared with PYTHIA Tune Z 1 & Z 1 C. Tune Z 1 C is not too bad but a bit off on the p. T dependence! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 40
Particle Ratios versus PT Æ CMS NSD data on the Cascade-+Anti. Cascade- Æ CMS NSD data on the Cascade-+Anti. Cascadeto Lambda+Anti. Lambda ratio versus p. T at 7 to 2 Kshort ratio versus p. T at 7 Te. V (|Y| < 2) compared with PYTHIA Tune Z 1 & Z 1 C. Tune Z 1 C is not too bad but a bit off on the p. T dependence! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 41
Particle Ratios versus PT Tails of the p. T distribution. Way off due to the wrong p. T! Æ ALICE INEL data on the charged kaons to charged pions ratio versus p. T at 900 Ge. V (|Y| < 0. 75) compared with PYTHIA Tune Z 1 & Z 1 C. Æ ALICE INEL data on the charged kaon to charged pion rapidity ratio at 900 Ge. V compared with PYTHIA Tune Z 1 C is not too bad but a way off on the p. T dependence! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 42
Particle Ratios versus PT Tails of the p. T distribution. Way off due to the wrong p. T! Æ ALICE INEL data on the Proton+Anti. Proton to Æ ALICE INEL data on the Proton+Anti. Proton charged pions ratio versus p. T at 900 Ge. V (|Y| < to charged pion rapidity ratio at 900 Ge. V 0. 75) compared with PYTHIA Tune Z 1 & Z 1 C. Tune Z 1 C is not too bad but way off on the p. T dependence! Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 43
Fragmentation Summary ÆNot too hard to get the overall yields of baryons and strange particles roughly right at 900 Ge. V and 7 Te. V. Tune Z 1 C does a fairly good job with the overall particle yields at 900 Ge. V and 7 Te. V. Warning! The Tune Z 1 C fragmentation ÆPT Distributions: PYTHIA does notmay describe correctly the p. T distributions parameters cause problems fitting data. None If so of the fragmentation of heavy particles (MC softer thanthe the. LEP data). must understand why! parameters I have looked atwe changes the p. T distributions. Hence, if one We dop not want one tune for looks at particle ratios at large you can see big discrepancies between T +e- and another one for e data and MC (out in the tails of the distributions)! hadron-hadron collisions! ÆATLAS Tuning Effort: Fragmentation flavor tuning at the one of the four stages. ÆOther Fragmentation Tuning: There is additional tuning involving jet shapes, FSR, and ISR that I did not have time to include in this talk. Boost 2011, Princeton, NJ May 23, 2011 Rick Field – Florida/CDF/CMS 44
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