Strange and Charm Probes of Hadronization of Bulk Matter

at RHIC

International Symposium on Multi-Particle Dynamics

Aug 9-15, 2005

Huan Zhong Huang

University of California at Los Angeles

Probes of Dense Matter in Nature

Volcanic high pT -- Strombolian eruption Volcanic mediate pT – Spatter (clumps)

Volcanic low pT – Bulk matter flows

Outline

1) Features of RCP and v2 for Particle Production at Intermediate pT

2) Charm RAA and v2

3) Hadronization of Defined Partonic Matter

4) Implications for QCD Matter at Hadronizationand LQCD Expectation

Nuclear Modification Factors

ddp

Nd

collddpNd

TAA

T

pp

T

AA NpR 2

2

/)(

Use number of binary nucleon-nucleon collisions to gauge the colliding parton flux:

N-binary Scaling RAA or RCP = 1 simple superposition of independent nucleon-nucleon collisions !

Peripheralcoll

T

Centralcoll

TTCP

NddpNd

NddpNd

pR

]/[

]/[

)( 2

2

Fragmentation sets in at pT > 5.5 GeV/c or so !!

Fragmentation

Meson-Baryon Scaling at Intermediate pT !!

There is something special at intermediate pT even in neutral pion and eta too !!

Particle Dependence of RCP(RAA)

Particle production at the intermediate pT

(2-5 GeV/c) 1) meson-baryon yields depend on

collision centrality (parton density)

2) Meson-baryon scaling – the dependenceis only on particle-type (meson versusbaryon), not explicitly on particle mass.

Elliptic Flow Parameter v2

y

x

py

px

coordinate-space-anisotropy momentum-space-anisotropy

Initial/final conditions, dof, EOS

1i

Ritttt

))ψcos(i(2v1dydpp

dN

2π

1

dyddpp

dN

y

Dynamical Origin of Elliptic Flow

V2 in the high pT region: Due to parton energy loss? Particle dependence of v2 ?

Collective Pressure

High pressure gradientLarge expansion velocity

Small expansion velocity

pT dependent !

Surface Geometrical Phase Space

Surface Emission PatternHigh particle density

Low particle density

pT independent ! orpT dependence may comefrom surface thickness (pT)

x

STAR

PHENIX

Particle Dependence of v2

Baryon

Meson

Unique baryon and meson difference !!

Run II

PHENIX (open symbols): Phys. Rev. Lett. 91, 182301 (2003)

Very Much Improved Data !!Meson-Baryon Scaling in v2 at Intermediate pT !!

solid: STARopen: PHENIX PRL91(03)

Constituent Quark Degree of Freedom

Why does the meson-baryon scaling work so well ?

Quark Cluster Formation from Strongly Interacting Partonic Matter

Volcanic mediate pT – Spatter (clumps)

Mesons – effective DOF 2Baryons – effective DOF 3 when formed from the bulk partonic matter !

Particle v2 may be related to quark matter azimuthal anisotropy !!

Multi-Parton Dynamics for Bulk Matter Hadronization

Essential difference:Traditional fragmentation particle properties mostly determined by the leading quark !Emerging picture from RHIC data (RAA/RCP and v2) all

constituent quarks are almost equally important in determining particle properties !

v2 of hadron comes from v2 of all constituent quarks !

The fact that in order to explain the v2 of hadrons individual constituent quarks (n=2-meson,3-baryon) must have a collective elliptic flow v2 and the hadron v2 is the sum of quark v2 Clear Evidence for Deconfiement !

1.13 0.09(stat.) 0.42(sys.) mb in 200GeV minbias Au+Au collsions

Total charm Binary Scalingsuppression at high pT

J/psi not significantly enhancedContrary to ReC- models

Total Charm Production Binary Scaling !

STAR Preliminary

Does Charm Quark Flow Too ?

Reduce Experimental Uncertainties !!Suppression in RAA Non-zero azimuthal anisotropy v2 !

Non-photonic Electrons Strongly Suppressed Too !

Beauty and Charm Contributions ? Energy Loss of Heavy Quarks?

STAR and PHENIX agree

J/psi is suppressed in central Au+Au Collisions !

Factor ~ 3 the same as that at SPS

Satz: Only states are screened both at RHIC and SPS.

Alternative: Larger suppression in J/psi at RHIC due to higher gluon density, but recombination boosts the yield up !

V2 of J/psi

V2 of J/psi can differentiate scenarios !

pQCD direct J/psi should have no v2 !

Recombination J/psi can lead to non-zero v2 !

The case for partonic DOF/Deconfinement can be made with strange vector meson

cannot be made from KK coalescence !

Summary

Effective partonic DOF has been observed to be important for Hadronization of Bulk Partonic Matter

Empirically the Parton Degrees of Freedom Scale as the Number of Constituent Quarks (n=2 for M, 3 for B)

If So, the Dense Matter Must Be Deconfined

The Missing Links

The Initial State from the Collision must be dominated by gluons (Temperature?) Parton Evolutions (?)At the Hadronization Stage the dominate degrees of freedom are constituent quarks (or quasi-hadrons) (Empirical)What is the parton evolution dynamics??

Is this what spectral function result from LQCD implies?

Empirically the dense matter with collective motions of constituent quark degrees of freedom must be preceded with a deconfined partonic matter, BUT we do not have any experimental indication that this is a phase transition !

The End

Strange quark dynamics are not significantly different from light quarks

Partonic Collectivity at RHIC!

Particle Dependence of RCP

suppression

Run II Data

Rcp={Yield/Ncoll}Central

{Yield/Ncoll}Peri

pT Scales and Physical Processes

RCPThree PT Regions:

-- Fragmentation

-- multi-parton dynamics (recombination or coalescence or …)

-- Hydrodynamics (constituent quarks ? parton dynamics from gluons to constituent quarks? )

Two Particle Jet-like Correlations

Jet-like two particle correlations (e.g., trigger particle 4-6 GeV/c, associated particle 2-4 GeV/c) :

These correlations cannot be easily explained in terms of recombination/coalescence scenario !

But 1) the effect of resonances on the two particle correlations has not be adequately addressed 2) trigger biases – with two high pT particles the initial parton is considerably harder than if only one high pT particle

is produced. Fragmentation region pT > 5.5 GeV/c 3) low level two particle correlations in the soft region can be

accommodated in recombination/coalescence(wave induced correlation?)