Pt-N correlation analysis for pp collisions in the PYTHIA framework

Pt-N correlation analysis for pp collisions in the PYTHIA framework

A. Asryan, D. Derkach, G. Feofilov

2008 Jan 06 Spåtind, The 20th Nordic Particle Physics Meeting

Saint-Petersburg State University

Outline

Introduction, main goals, current priorities Experimental data overview PYTHIA v6.325 studies Summary

2008 Jan 06 A. Asryan, Spåtind, The 20th 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 LHCA.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. 6.8.1, https://edms.cern.ch/document/682648/1

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-2002


Experiments on p-p and p-anitp collisionsEnergy,

GeVName of the machine Name of experiment or detector Type

17 SPS (Super Proton

Synchroton), CERN

NA49, Large Acceptance Hadron Detector LAB

19

22SPS (Super Proton

Synchroton), CERN

NA5

NA22

LAB

32

63

540

ISR (Intersecting Storage

Rings), CERN

ABCCDHW (Ames, Bologna, CERN, College de France, Dortmund, Heidelberg, Warszawa),

SFM (Split Field Magnet)

CMS

200

900

SppS (Super Proton Antiproton Synchroton), CERN

UA1 (Underground Area),

a 4-pi Solid Angle Detector

CMS

1800 Tevatron, Fermilab CDF (The Collider Detector at Fermilab) CMS

1800 Tevatron, Fermilab E375 (D0 at Fermilab) CMS

NA49 collab. arXiv:hep-ex/0311009 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) 599


Correlations <pt> - <Nch>

Mean transverse momenum vs multiplicity correlations gives us information about collectiviy effects in pp collisions

<pt> = f(<Nch>)

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 2006


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-2006-031 2008 Jan 06 A. Asryan, Spåtind, The 20th 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 energiesTwo 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


PYTHIA Parameters and SwitchesParameters Description

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 PYTHIAModel 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/0308153, LU TP 03–38, August 2003


2,03,0

4,05,0

6,07,0

8,09,0

10,11,

12,

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0,8

0,9

number of strings

PYTHIA PARP3 100%

PYTHIA PARP1 90%

PYTHIA PARP4 33%

PYTHIA PARP6 00%

EPEM Model

“Gluon String Fusion” EffectsNumber 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


Results: PYTHIA pt-n Correlations

p-p at 17 GeV p-pbar at 31 GeV

multiplicity multiplicity

mea

n tr

ansv

erse

mom

entu

mppbar collisions

31 GeV

|y| ≤ 2

ISR

pp collisions

17 GeV

1.1 ≤ y ≤ 2.6

ISR (NA5)



p-pbar at 200 GeV p-pbar at 540 GeV


mea

n tr

ansv

erse

mom

entu

m

ppbar collisions

200 GeV

|η| ≤ 2.5

SPS

ppbar collisions

540 GeV

|η| ≤ 2.5

FNAL (E735)



p-pbar at 900 GeV p-pbar at 1800 GeV


mea

n tr

ansv

erse

mom

entu

m

ppbar collisions

900 GeV

|η| ≤ 2.5

FNAL (E735)

ppbar collisions

1800 GeV

|η| ≤ 2.5

FNAL (CDF)


Results: PYTHIA Parameters

Energy,

GeV

PYTHIA

Parameters

17 31 200 540 900 1800

MSUB(91) 0 0 1 1 1 1

MSUB(92) 1 1 1 1 1 1

MSUB(93) 1 1 1 1 1 1

MSUB(94) 1 1 1 1 1 1

MSUB(95) 0 0 1 1 1 1

MSUB(96) 1 1 1 1 1 1

PARP(85) 90% 90% 90% 90% 90% 90%

PARP(86) 95% 95% 95% 95% 95% 95%

1800 GeV with EPEM Values of parameters

ppbar collisions

1800 GeV

|η| ≤ 2.5

FNAL (CDF)

Low pt production

Elastic scattering

Single diffraction

Single diffraction

Double diffraction

Semihard QCD

Gluon string fusion

Gluon string formation



Predictions for LHCp-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 in1) 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. 6.8.1, https://edms.cern.ch/document/682648/1

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, 05-09 December 2005, Erice, Italy, http://agenda.cern.ch/fullAgenda.php?ida=a057183

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 2006 http://physicschool.web.cern.ch/PhysicSchool/

4) 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 2006

5) 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 2006 http://indico.cern.ch/conferenceDisplay.py?confId=5251

6) 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 2006

7) N.Armesto, A.Asryan, D.Derkach, G.Feofilov, «Analysis of p_t-n correlation in pp and p-antip elementary collisions», in preparation


Summary


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 200-900 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


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 05-112-5016

Thank you for your attention


Backup Slides

PSM (Parton String Model) EPEM (Effective pomeron exchange model) ROOT framework

2008 Jan 06 A. Asryan, Spåtind, The 20th 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)


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

<pt> vs E

<pt> vs nch


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 2006


n

t

ch

Nynk

n

l

lzp

t tn

mp

N

ynke

l

ze

nzpd

tkdN ch

))(

exp(!

)2()

!1(

),,( 222

1

02

Multi Pomeron Exchange Model (N. Armesto et al., ALICE INT-NOTE/PHY, to be published)

- parameter that accounts effectively collectivity

n

t

ch

Nynk

n

l

lzp

t t

mp

N

ynke

l

ze

nzpd

tkdN ch

))(

exp(!

)2()

!1(

),,( 222

1

02

= =

k, t - parameters2008 Jan 06 A. Asryan, Spåtind, The 20th Nordic Particle Physics Meeting Backup 23

<pt>Nch-Nch correlations, EPEM(17-1800 GeV)


Fit results:

10 100 1000

-0,5

0,0

0,5b

CM energy, GeV


Fit results: t

10 100 10000,0

0,1

0,2

0,3

0,4

0,5

0,6t,

Gev

2

CM Energy, GeV


Fit results: k

10 100 10000,00,20,40,60,81,01,21,41,61,82,0

k

CM Energy


ROOT framework

Pt-N correlation analysis for pp collisions in the PYTHIA framework

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