L. Bravina (UiO) for the

heavy-ion theory groups from

UiB (leader – L. Csernai) and

UiO (leader – L. Bravina)

RECFA meeting (Oslo, 15.05.2009) RECFA meeting (Oslo, 15.05.2009)

Current projects: Bulk particle production in soft and hard processes;

anisotropic flow; equation of state; particle freeze-out;

role of resonances; HBT correlations; jet quenching; shadowing ...

HYDJET

FASTMCI. Lokhtin et al., Comput. Phys. Commun. 180 (2009) 779N. Amelin, … L.B. … et al., Phys. Rev. C 77 (2008) 014903

K. Tywoniuk, L.B. et al., Phys. Lett. B 657 (2007) 170

HYDJET++

heavy-ion collisions in each rescattering there is

a certain probability for particle production

the projectile becomes large compared to the target

interacts simultaneously with the whole system effectively less interaction - shadowing dramatic change of space-time picture

K. Tywoniuk, L.B. et al., J. Phys. G 35 (2008) 104156A. Capella, L.B. et al., Eur. Phys. J. C 58 (2008) 437

15.05.2009

7

weaker comover suppression at forward weaker recombination at forward stronger initial state effects!

Capella, Bravina, Ferreiro, Kaidalov, Tywoniuk, Zabrodin arxiv: 0712.4333

1

)])(cos[)(21(2

1

nrtn npv

d

dN

12 , tan ( )cos 2( ) y

xrv

p

p

Soft physics: Elliptic flowSoft physics: Elliptic flow

Flow with HYDJET++ model: study of jet influence and resonance decay on flow of different particles.

Jet influence : inverse of mass ordering at pT ≈ 2 GeV

Resonance decay influence: increase of v2.

The model possesses crossing of baryon and meson branches.Hydrodynamics gives mass ordering of v2

L. B., G. Eyyubova et al.,arXiv:0903.5175

Influence of resonance decays for Influence of resonance decays for different types of particles on vdifferent types of particles on v22 value value

30% 20%

44% 39%

L. B., G. Eyyubova et al., arXiv:0903.5175

Because of the kinematics of the decay, protons carry practically the same flow as mother Δ particles while pion flow is shifted to low pT

Protons flow : direct and from Δ decays Pions flow : direct and from Δ decays

Pions flow : direct and from ω decays Pions flow : direct and from ρ decays

4. EQUILIBRATION IN THE 4. EQUILIBRATION IN THE CENTRAL CELLCENTRAL CELL

Kinetic equilibrium:Kinetic equilibrium: Isotropy of velocity distributionsIsotropy of velocity distributions

Isotropy of pressureIsotropy of pressure

Thermal equilibrium: Thermal equilibrium: Energy spectra of particles are Energy spectra of particles are described by Boltzmann distributiondescribed by Boltzmann distribution

Chemical equlibrium:Chemical equlibrium: Particle yields are reproduced by SM with the same values of Particle yields are reproduced by SM with the same values of

QUARK-GLUON STRING MODEL (QUARK-GLUON STRING MODEL (QGSMQGSM) ) AND AND ULTRA-RELATIVISTIC QUANTUM MOLECULAR ULTRA-RELATIVISTIC QUANTUM MOLECULAR DYNAMICS (DYNAMICS (URQMDURQMD))

Excitation of color neutral stringsExcitation of color neutral strings

EOS: HOW DENSE CAN BE THE EOS: HOW DENSE CAN BE THE MEDIUM? MEDIUM?

”” B

ig”

cell

(V

= 5

x5x5

fm

^3

Big

” ce

ll (

V =

5x5

x5 f

m^

3 ))

Dramatic differences at the non-equilibrium stage; after beginning of Dramatic differences at the non-equilibrium stage; after beginning of kinetic equilibrium the energy densities and the baryon densities are the kinetic equilibrium the energy densities and the baryon densities are the same for ”small” and ”big” cell same for ”small” and ”big” cell

““ Sm

all”

cel

l (V

=S

mal

l” c

ell (

V =

> 0

)>

0)

L. B

. et

al.,

Ph

ys. R

ev. C

78

(200

8)

0149

07

EOS IN THE CELL: OBSERVATION EOS IN THE CELL: OBSERVATION OF KNEEOF KNEE

temperature vs. chemical potentialstemperature vs. chemical potentials

Although the “knee” is similar to that in 2-flavor lattice QCD, it is Although the “knee” is similar to that in 2-flavor lattice QCD, it is related to inelastic (chemical) freeze-out in the system related to inelastic (chemical) freeze-out in the system

S. Ejiri et al., PRD 73 S. Ejiri et al., PRD 73 (2006) 054506(2006) 054506

L.B. et al., PRC 78 (2008) 014907;E. Zabrodin, L.B. et al,arXiv:0902.4601

M.S. Nilsson, ”LHC and beyond” (Lund, Feb. 2009)

M.S. Nilsson , ”LHC and beyond” (Lund, Feb. 2009)

M.S. Nilsson , L.B. et al. (to be submitted)

DetectorDetector

M.S. Nilsson , L.B. et al. (to be submitted)

L. Csernai , talk at SQM’08 (Beijing, Oct. 2008)

8.

9. QGSM PREDICTIONS FOR 9. QGSM PREDICTIONS FOR PP AT LHCPP AT LHC

Gribov’s Reggeon Calculus + string phenomenologyGribov’s Reggeon Calculus + string phenomenology

At ultra-relativistic energies: multi-Pomeron scattering, single and double diffraction, and jets (hard Pomeron exchange)

RAPIDITY AND PRAPIDITY AND PTT SPECTRA: SPECTRA: MODEL VS. DATA MODEL VS. DATA

Inelastic collisionsInelastic collisions

NSD collisionsNSD collisions

Description of both pseudorapidity Description of both pseudorapidity and transverse momentum and transverse momentum distributions seems to be gooddistributions seems to be good

J. Bleibel, L. B., E. Zabrodin et al., (in progress)

LH

C

pre

dic

tion

s

PREDICTIONS FOR PP PREDICTIONS FOR PP @ LHC@ LHC

QGSM: extended longitudinal scaling in p+p collisions holdsQGSM: extended longitudinal scaling in p+p collisions holds

High-multiplicity tail High-multiplicity tail isis pushed up, whereas pushed up, whereas maximum of the maximum of the distribution is shifted distribution is shifted towards small values towards small values of of zz

At energies below 100 At energies below 100 GeV different GeV different contributions overlap contributions overlap strongly, whereas at strongly, whereas at higher energies – higher energies – more multi-string more multi-string processesprocesses

2

46 8

=> Enhancement of high multiplicitiesEnhancement of high multiplicities

VIOLATION OF KNO SCALING VIOLATION OF KNO SCALING AT LHCAT LHC

Summary and outlookSummary and outlook• LHC is a LHC is a discovery machine discovery machine for both hard and soft for both hard and soft

physics in HI collisionsphysics in HI collisions• Event generators are an indispensable tool for planing Event generators are an indispensable tool for planing

the experiments and analysis of datathe experiments and analysis of data• => Further development of existing MC generators=> Further development of existing MC generators• HI theory groups in Oslo and Bergen are utilizing it HI theory groups in Oslo and Bergen are utilizing it

to study : to study : EOS, elliptic flow, particle freeze-out, HBT EOS, elliptic flow, particle freeze-out, HBT correlations of unlike particles, particle-jet correlations of unlike particles, particle-jet correlations, heavy quark production in a large pT correlations, heavy quark production in a large pT range, scaling propertiesrange, scaling properties

Theory Group at UiO:I.C. Arsene, L. Bravina, G. Eyyubova, R. Kolevatov, M.S. Nilsson, K. Tywoniuk*, E. Zabrodin

FIAS, Frankfurt M. Bleicher, G. Burau, H. StockerMSU, Moscow I. Lokhtin, L. Malinina*, A. SnigirevLPT, Orsay A. CapellaITEP, Moscow A. Kaidalov, K. BoreskovITP, Tuebingen J. Bleibel, C. Fuchs, A. FaesslerBITP, Kiev Yu. Karpenko, Yu. SinyukovIGFAE, Santiago de Compostella E.G. Ferreiro, K. Tywoniuk*

cooperation with ALICE experimental group

other collaborators:

21 – papers in international refereed journals10 – published conference contributions29 – oral and poster presentations (for 5 years)

Theory Group at UiB:L. Csernai, S. Hotvath, Yun Cheng, M. Zetenyi*

FIAS, Frankfurt I. Mishustin, E. Molnar, D. RischkeUni.-Minnesota J. KapustaBNL L. McLerranLANL, Los-Alamos D. StrottmanECM, Barcelona V.K. Magas RMKI, Bud M. Zetenyi*

cooperation with ALICE experimental group

other collaborators:

19 – papers in international refereed journals 7 – published conference contributions17 – oral and poster presentations (for 5 years)

Back-up Slides

the diagrams corresponding to ”classical” rescatterings are suppressed at high energies!

Gribov trick: Glauber is OK after all! Almost...

have to take into account diffractive intermediate states!

E

1(2)

totσ + + . . .totσ

W. Busza, JPG 35 (2008) 044040 W. Busza, JPG 35 (2008) 044040

Extrapolation of NSD pp data to LHC using ㏑√ s scaling of the width and height of the distribution

W. Busza, JPG 35 (2008) 044040 W. Busza, JPG 35 (2008) 044040

Example of extended longitudinal scaling in different reactions

e+e－

Basic assumption: scaling of inclusive spectra within the whole kinematically allowed region of xF (or c.m. y) In addition: existence of central area , where is assumed.

R. Feynman, PRL 23 (1969) 1415; also in ”Photon-hadron interactions”

0 0Fx x x 0 (0.1 0.2)x

In terms of rapidity

*0 0ln[ / ] ln[ / ]T Tx s m y x s m

(1) Logarithmic rise of the central rapidity region with energy

(2) Fragmentation regions are fixed

(3) Main contribution to mean multiplicity comes from the central area

(5) Contribution from the fragmentation regions is energy independent

(4) In the central area particle density does not depend on energy and rapidity

*0( ) 2 ln( / )Ty x s m

*0( ) ln(1/ )y x

0ln( / )Tn x s m

*( , ; ) ( )T Ty p s p

W. Busza, JPG 35 (2008) 044040 W. Busza, JPG 35 (2008) 044040 UA5 Collab., Phys. Rep. 154 (1987) 247UA5 Collab., Phys. Rep. 154 (1987) 247

Charged particle pseudorapidity density at as a function of √s

Violation of Feynman scaling,but ext. long. scaling holds?!

PREDICTIONS FOR P+P PREDICTIONS FOR P+P @ LHC@ LHC

QGSM: pseudorapidity distribution of particlesQGSM: pseudorapidity distribution of particles

LHC

VIOLATION OF VIOLATION OF ELSELS IN A+A AT IN A+A AT LHC? LHC?

Statistical thermal model: ELS will be violated in A+A @ LHC. What about Statistical thermal model: ELS will be violated in A+A @ LHC. What about p+p ?p+p ?

J. Cleymans, J.Struempfer, L.Turko, PRC 78 (2008) 017901

WHY SCALING HOLDS IN THE WHY SCALING HOLDS IN THE MODEL? MODEL?

In string models both In string models both FSFS and and ELS ELS holds in the fragmentation regionsholds in the fragmentation regions

2 21 2

2

Correlation function

Particles are uncorrelated if

Particle inclusive cross section

In the fragmentation region of

( , ) exp{ ( )}

1

1 2

( , , )

p

i j i j

i j

i i iTi

i iT

Consider now inclusive process

C y y y y

y y y

i X

d y y y y pf

dy d p

1 2 1 2

21

article1

Inclusi

1 , 1

n

ve density

/ ( , )

i i

i i inel i iT

y y y y y y

f y y p

Shor

t ran

ge c

orre

latio

ns( )

1max

( ) 2

exp{ ( )

therefo e

)

r

}

( ,

iiF i

ii F iT

px y y

p

n x p

KOBA-NIELSEN-OLESEN KOBA-NIELSEN-OLESEN ((KNOKNO) SCALING) SCALING

Z.Koba, H.B.Nielsen, P.Olesen, NPB 40 (1972) 317Z.Koba, H.B.Nielsen, P.Olesen, NPB 40 (1972) 317

Experimental data: KNO scaling holds in Experimental data: KNO scaling holds in hhhh collisions collisions up to up to √s = 53 GeV (ISR)√s = 53 GeV (ISR)

They claim that if Feynman scaling holds, then the multiplicity distribution isindependent of energy except through the variable

/

( ) 1( )

( )n

ntot

z n n

s nP s

s n n

VIOLATION OF KNO SCALINGVIOLATION OF KNO SCALING

A.B.Kaidalov, K.A.Ter-Martirosyan, PLB 117 (1982) 247A.B.Kaidalov, K.A.Ter-Martirosyan, PLB 117 (1982) 247 UA5 Collaboration, Phys. Rep. 154 (1987) 247UA5 Collaboration, Phys. Rep. 154 (1987) 247 N.S.Amelin, L.V.Bravina, Sov.J.Nucl.Phys. 51 (1990) 133 N.S.Amelin, L.V.Bravina, Sov.J.Nucl.Phys. 51 (1990) 133

√√ss

Charged-particle Charged-particle multiplicity distributions multiplicity distributions in the KNO variables in in the KNO variables in nondiffractive nondiffractive antiproton-proton antiproton-proton collisions at collisions at √s = 546 GeV √s = 546 GeV andand

53 GeV 53 GeV

2

In-plane

Dispersion of emitter velocities x-p correlation: interference dominated by pions from nearby emitters

Interference probes only a part of the source Interferometry radii decrease with pair velocity

Pt=160 MeV/cPt=380 MeV/c

Rout Rout

Correlation radii and space-time structure of the source.

cos qx=1-½ (qx)2… exp(-Rx2qx2 –Ry2qy2 -Rz2qz2 -Rxz2qx qz)

Rx2 =½ (x-vxt)2, Sensitive to emission time

Ry2 =½ (y)2 ,

Rz2 =½ (z-vzt)2 Sensitive to longitudinal extent

Sensitive to transverse extent

Expanding source

time

dN/dt

PCM & clust. hadronization

NFD

NFD & hadronic TM

PCM & hadronic TM

CYM & LGT

string & hadronic TM

• p-space observables well-understood within hydrodynamic framework

→ hope of understanding early stage

• x-space observables not well-reproduced

• correct dynamical signatures with incorrect dynamic evolution?

• Too-large timescales modeled?• emission/freezeout duration (RO/RS)• evolution duration (RL)

Heinz & Kolb, hep-ph/0204061

This picture is borrowed from 2nd Warsaw Meeting on Particle Correlations and Resonances in Heavy Ion Collisions Mercedes López Noriega STAR collab.2003

hadronization

initial state

pre-equilibrium

QGP andhydrodynamic expansion

hadronic phaseand freeze-out

PCM & clust. hadronization

NFD

NFD & hadronic TM

PCM & hadronic TM

CYM & LGT

string & hadronic TM

dN/dt

1 fm/c 5 fm/c 10 fm/c 50 fm/c time

Kinetic freeze out

Chemical freeze out

RHIC side & out radii: 2 fm/cRlong & radii vs reaction plane: 10 fm/c

Bass’02

This picture is borrowed from R. Lednicky talk at Nantes meeting, 2006

Influence of jet fragmentation on correlation radii at LHC

STAR

HYDJET++, ptmin>7 GeV/c

HYDJET++, ptmin>10 GeV/c

HYDJET++, hydro only

Pure hydro (no jets):R(LHC) > R(RHIC)Ptmin=10 GeV/c(~25% jet contribution): R(LHC) ~ R(RHIC)Ptmin=7 GeV/c(~55% jet contribution): R(LHC) < R(RHIC)! (especially Rlong) due to the significant influence of “jet-induced” hadrons, which are emitted on shorter space-time scales than soft hadrons.

It seems quite non-trivial prediction...

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