Pt-N correlation analysis for pp collisions in the PYTHIA framework A. Asryan, D. Derkach, G. Feofilov 2008 Jan 06 Spåtind, The 20 th Nordic Particle Physics Meeting Saint-Petersburg State University

Outline  Introduction, main goals, current priorities  Experimental data overview  PYTHIA v6.325 studies  Summary 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 2

Introduction  There are collectivity effects in AA collisions  Nucleon-nucleon collisions are basic processes for AA collisions studies  In such elementary collisions some collectivity effects could be also observed and analyzed  Analysis of these collectivity effects gives us detailed information about physical processes in collisions  Long range correlations were proposed as analysis tool for ALICE at the LHC A.Asryan, D.Derkach, M.Braun, G.Feofilov, A.Ivanov, R.Kolevatov, V.Kondratiev, P.Naumenko, V.Vechernin, “Long-rangec Studies In ALICE”, ALICE Physics Performance Report, Vol.2, Chap , P.A.Bolokhov, M.A.Braun, G.A.Feofilov, V.P.Kondratiev, V.V.Vechernin, “Long- Range Forward-Backward p_t and Multiplicity Correlations Studies in ALICE”, ALICE-INT Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 3

Experiments on p-p and p-anitp collisions Energy, GeV Name of the machineName of experiment or detectorType 17SPS (Super Proton Synchroton), CERN NA49, Large Acceptance Hadron DetectorLAB SPS (Super Proton Synchroton), CERN NA5 NA22 LAB ISR (Intersecting Storage Rings), CERN ABCCDHW (Ames, Bologna, CERN, College de France, Dortmund, Heidelberg, Warszawa), SFM (Split Field Magnet) CMS SppS (Super Proton Antiproton Synchroton), CERN UA1 (Underground Area), a 4-pi Solid Angle Detector CMS 1800Tevatron, FermilabCDF (The Collider Detector at Fermilab)CMS 1800Tevatron, FermilabE375 (D0 at Fermilab)CMS NA49 collab. arXiv:hep-ex/ A. Breakstone et al. (ABCDHW Collaboration), Phys. Lett. 132B (1983) 463 UA1 collab., Nucl Phys 335B (1990) 261 F.Abe et.al, Phys.Rev.Lett. 61 (1988) 1819 C.De Marzo et al. Phys. Rev. 29D (1984) 363 V.V. Aivazyan et al., Phys.Lett. 209B (1988) 103 T. Alexopoulos et al., Phys. Lett. 336B (1994) Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 4

Correlations - Mean transverse momenum vs multiplicity correlations gives us information about collectiviy effects in pp collisions = f( ) A.Asryan, D.Derkach, G.Feofilov, “Analysis of p_t-n_ch Correlation in pp and p-antip Collisions”, XVIII Baldin ISHEPP, Dubna, Russia, 27 September Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 5

Main features of the data N.Armesto, D.Derkach, G.Feofilov, “Analysis of PtN correlation in p-p and p-antip elementary collisions from ISR to FermiLab energies and projection towards ALICE at the LHC”, ALICE-INT-NOT Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 6  Rise of the mean pt value with the multiplicity  An indication on flattening at the highest multiplicity  Effect grows with the collision energy  Positive ptn correlations at energies higher than 31 GeV, negative PtN correlations at lower energies  Two families of correlation functions with different pt values at Nch = 0

PYTHIA pt-n Correlation Studies  PYTHIA v6.325 parameters and tunings  PYTHIA collectivity effects as Model of Multiple Interactions  Effect of colour correlations, “gluon string fusion” phenomena  PYTHIA correlations for p-p collisions from 17 GeV to 1.8 TeV 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 7

PYTHIA Parameters and Switches ParametersDescription MSUB(91)Elastic Scattering MSUB(92)Single Diffraction AB -> XB MSUB(93)Single Diffraction AB -> AX MSUB(94)Double Diffraction MSUB(95)Low Pt Production MSUB(96)Semihard QCD PARP(85) D=33% “Colour correlations” - probability that an additional interaction in the multiple interaction formalism gives two gluons, with colour connections to ‘nearest neighbours’ in momentum space PARP(86) D=66% “Gluon-gluon string formation” - probability that an additional interaction in the multiple interaction formalism gives two gluons, either as described in PARP(85) or as a closed gluon loop. Remaining fraction is supposed to consist of quark–antiquark pairs Collectivity in PYTHIA Model of multiple interactions T. Sjöstrand, “Monte Carlo Generators”, European School of High-Energy Physics 2006, Aronsborg, Sweden, 27 June 2006 Torbjörn Sjöstrand, Leif Lönnblad, Stephen Mrenna, Peter Skands, “PYTHIA 6.3 Physics and Manual”, hep-ph/ , LU TP 03–38, August Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 8

“Gluon String Fusion” Effects Number of strings distribution ppbar at 200 GeV Effective Multi Pomeron Exchange Model (EPEM): N. Armesto, A. Asryan, D. Derkach, G. Feofilov, “Analysis of pt-Nch Correlations in pp and p-antip Collisions”, ALICE physics week, Erice, Italy, 09 December 2005 “String Fusion” Variations ppbar at 900 GeV 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 9

Results: PYTHIA pt-n Correlations p-p at 17 GeV p-pbar at 31 GeV multiplicity mean transverse momentum ppbar collisions 31 GeV |y| ≤ 2 ISR pp collisions 17 GeV 1.1 ≤ y ≤ 2.6 ISR (NA5) 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 10

Results: PYTHIA pt-n Correlations p-pbar at 200 GeV p-pbar at 540 GeV multiplicity mean transverse momentum ppbar collisions 200 GeV |η| ≤ 2.5 SPS ppbar collisions 540 GeV |η| ≤ 2.5 FNAL (E735) 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 11

Results: PYTHIA pt-n Correlations p-pbar at 900 GeV p-pbar at 1800 GeV multiplicity mean transverse momentum ppbar collisions 900 GeV |η| ≤ 2.5 FNAL (E735) ppbar collisions 1800 GeV |η| ≤ 2.5 FNAL (CDF) 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 12

Results: PYTHIA Parameters Energy, GeV PYTHIA Parameters MSUB(91) MSUB(92) MSUB(93) MSUB(94) MSUB(95) MSUB(96) PARP(85)90% PARP(86)95% 1800 GeV with EPEM Values of parameters ppbar collisions 1800 GeV |η| ≤ 2.5 FNAL (CDF) Low p t production Elastic scattering Single diffraction Double diffraction Semihard QCD Gluon string fusion Gluon string formation 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 13

2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 14 Predictions for LHC p-antip collisions at 5.5 TeV for ALICE LHC Difference between these models is that in PYTHIA we keep collectivity effects the same for all energies. EPEM has a parameter which depends on collisions energy.

Results were presented in 1) A.Asryan, D.Derkach, M.Braun, G.Feofilov, A.Ivanov, R.Kolevatov, V.Kondratiev, P.Naumenko, V.Vechernin, «Long-range Correlation Studies In ALICE», ALICE PPR, Vol.2, Chap , 2) N.Armesto, A.Asryan, D.Derkach, G.Feofilov, «Analysis of p_t-n_ch Correlations in pp and p-antip Collisions», ALICE Physics Week, December 2005, Erice, Italy, 3) A. Asryan, «PSM and PYTHIA Simulations for p-p and Heavy Ions Collisions», The 14-th European School of High-Energy Physics 2006, Aronsborg, Sweden, 22 June ) A.Asryan, D.Derkach, G.Feofilov, «Analysis of p_t-n_ch Correlation in pp and p-antip Collisions», XVIII Baldin ISHEPP, Dubna, Russia, 27 September ) A. Asryan, G. Feofilov, «Studies of pt-n correlation in proton collisions in the framework of PSM and PYTHIA generators», ALICE Week, Physics Forum, CERN, 11 October ) A.Asryan, D.Derkach, M.Braun, G.Feofilov, A.Ivanov, R.Kolevatov, V.Kondratiev, P.Naumenko, V.Vechernin, «Long-range Correlation Studies In ALICE», Journal of Physics G, Nuclear and Particle Physics, Vol 32 Number 10 October ) N.Armesto, A.Asryan, D.Derkach, G.Feofilov, «Analysis of p_t-n correlation in pp and p- antip elementary collisions», in preparation 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 15

Summary 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 16  Collectivity effects in PYTHIA (model of multiple interactions) are found to be important  PYTHIA v6.325 could be tuned for experimental PtN correlations description in GeV energy range with the same set of parameters  Predictions were made for ALICE LHC energies  Most of the features of PtN correlation analysis were rewritten in C++ in the ROOT+PYTHIA framework with *.root-format files and GUI

Future plans 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 17  PYTHIA v6.325 (probably slightly modified) is planned to be integrated into the PSM (parton string model event generator) for the following heavy ion collision simulations and analysis  Further development of standard classes and routines has to be made within AliROOT framework with ALICE detector geometry included  Using PYTHIA 8.1 with AliROOT framework should be the next task

Acknowledgements Author would like to thank T. Sjöstrand and K. Safarik for fruitful discussions, comments and advises. These studies were partially supported by INTAS Young Scientist Fellowship grant, INTAS Ref. Nr Thank you for your attention 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting 18

Backup Slides  PSM (Parton String Model)  EPEM (Effective pomeron exchange model)  ROOT framework 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting Backup 19

Parton String Model Generator  PSM is an implementation of parton string fusion model  PSM is able to simulate both pp and ion-ion collision events with different impact parameters  PSM have a String Fusion module, which allows to study this phenomena  PSM is based on PYTHIA v5.5 and JETSET v7.3 N.S. Amelin, N. Armesto, C. Pajares, D. Sousa, “Monte Carlo model for nuclear collisions from SPS to LHC energies”, Eur. Phys. J. C 22, 149–163 (2001) 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting Backup 20

PSM Results  PSM was tuned to describe simple observable such as mean transverse momentum and mean multiplicity for p-p and heavy ion collisions at wide energy range  We found that PSM is unable to simulate more complicated cases such as correlations between these observables  The reason seems to be PYTHIA A. Asryan, “PSM and PYTHIA Simulations for p-p and Heavy Ions Collisions”, 14-th European School of High-Energy Physics 2006, Aronsborg, Sweden vs E vs n ch 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting Backup 21

PSM pt-n Correlations in p-p p-p experimental data PSM simulations A.Asryan, D.Derkach, G.Feofilov, report at XVIII Baldin ISHEPP, Dubna, Russia, 27 September Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting Backup 22

Multi Pomeron Exchange Model (N. Armesto et al., ALICE INT-NOTE/PHY, to be published) - parameter that accounts effectively collectivity == k, t - parameters 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting Backup 23

Nch -N ch correlations, EPEM ( GeV) 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting Backup 24

Fit results: 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting Backup 25

Fit results: t 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting Backup 26

Fit results: k 2008 Jan 06A. Asryan, Spåtind, The 20 th Nordic Particle Physics Meeting Backup 27

ROOT framework