Loïc Grandchamp

Lawrence Berkeley National Laboratory

“Probing QCD with High Energy Nuclear Collisions”

Hirschegg, Jan. 16-22 ’05

with

H. van Hees, S. Lumpkins, R. Rapp, D. Sun

Quark(onium) Production in URHICs

Motivations / Introduction Charm & bottom in HI collisions

produced early, small HG int. ) probe the medium energy loss coalescence thermalization

two mass scales: mc ' 1.5 GeV, mb ' 5 GeV in-medium modifications

heavy-light systems, –symmetry restoration resonances in QGP, quarkonia above Tc

Quark(onium) evolution & timescalesNuclear absorption

Ncc frozen

Thermal QGP

Mixed phaseSuppression/Regeneration

Hadron gas

Thermal Freezeout

Free streaming

Outline This talk

Heavy quarks and quarkonia in matter Lattice QCD Charmonia in QGP, HG C-quark thermal equilibration Charmonium equilibrium numbers Rate equations

Quarkonium in A-A collisions Charmonium at SPS & RHIC ’/ ratio Lighter systems Bottomonium

Not in this talk Open-charm production in pp (expts. + Ncoll scaling) Nuclear suppression (nuc from expts.)

Lattice QCD heavy quark Free energy [Karsch et al. ’00] Reduction of the open charm threshold Even below Tc

Smooth transition across Tc ) medium effects: mc

¤, mD¤, ’/ ratio

Heavy quarks & lattice QCD Spectral functions from Lattice [Umeda et al. ’02]

Low-lying charmonia survive in the QGP Mass constant

Large width increase across Tc

Charmonium lifetimes

Quarkonium above Tc

gluodissociation[Bhanot, Peskin ‘79]

0 >> QCD

“quasifree”[LG + R. Rapp ’01]

0 » QCD

Reduced in-medium 0

) quasifree more efficient

) applicable for ’,

Quarkonium below Tc

Hadronic interactions (vacuum) Inefficient (small densities) Even for excited states

In-medium effects % inel. collisions & DD threshold

’fragile

J/ robust

[Navarra et al.]

M.Ex

CQM

QCD-SR

pQCD

[LG +

R. Rapp ’03]

P?-spectra: insensitive,

null effect [Batsouli etal. ‘02]

Similarly for D-meson from coalescence [Greco etal. ‘03]

PHENIX130AGeV

e±

D

Pythia

Thermal + flow

PHENIX200AGeV

D-meson coalescence

C-quark interactions: Thermalization ?

B

bottom

charm

Elliptic flow: v2(e§)

needs confirmation

Nf=4 QGP !?

[PHENIX Prelim]

[STAR Prelim]

Possible mechanism: [van Hees + Rapp ’04]

resonant open-charm rescatteringc + q ! “D” ! c + qisotropic ! more efficient than pQCD

Quarkonium equilibrium numbers

[LG + R. Rapp ’03]

Statistical hadronization at Tc Quarkonia above Tc ) regeneration in QGP Detailed balance:

Quarkonium evolution in URHICs

Thermal c-quark:

, Neq: medium effects

Link to Lattice QCD

Convolute over fireball expansion

Include feeddown Chemical off-equilibrium c

Thermal off-equilibrium R

[Braun-Munzinger +Stachel ’01 Gorenstein etal. ’02]

[Thews etal. ’01 Ko etal. ’02 LG + R. Rapp ‘02]

[LG + R. Rapp ’03]

Centrality dependenceSPS Pb(158 AGeV)-

PbRHIC 200 Au-Au

Suppression Regeneration

Charmonium in A-AExcitation

function

Transition “direct suppressed” “statistical”

SPSRHI

C

Charmonium in A-A

Medium effects:’/ ratio

Lighter systems

SPS In(158 AGeV)-In RHIC 200 Cu-Cu

QGP Suppression regime

Upcoming NA60 results

50% direct

50% regenerated

Onset of regeneration

Centrality dependenceMedium effects: ’/ ratio

NA60: In(158 AGeV)-In

Still sensitive to in-medium effects

Fireball thermalization in peripheral collisions ?

Model approaches at RHIC Suppression only [Kostyuk etal. ’02]

Statistical Hadronization [Andronic etal. ’02]

Suppression+Regeneration [Thews etal. ’03] equilibrium & off-equilibrium scenarios

) strong sensitivity to Ncc

Bottomonium in A-A

RHIC LHC

Suppression prevails even at LHC

) “Control experiment” for charm regeneration

[S. Lumpkins etal. ’05]

Model of charmonium production in A-A Survival of charmonia above Tc Reduction of the open charm threshold + Rate equations

SPS: charmonium suppressionRHIC: charmonium regeneration

Bottomonium suppression at RHIC & LHC Various observables, systems, energies

Outlook C-quark thermalization ?! V2(e§) needs confirmation V2(J/) P?-distributions

Conclusions

QGP

Quark(onium) production in URHICs

Extra Slides

Open Charm Production NN collisions

LO pQCD: K ~ 4-7 NLO: K ~ 2-3

pA collisions Scaling

AA collisions

• SPS central Pb-Pb

• RHIC central Au-Au

Primordial J/: Pre-Eq Effects

Nuclear absorption

AA collisions

L: nuclear path length nuc: 4.4 mb 50% effect in Pb-Pb at SPS

RHIC Nuclear absorption ?

NN collisions: ~ 1% of cc pairs form a quarkonium state pA collisions:

Thermal Fireball evolution Expanding thermal fireball

Trajectory in (B, T) plane at constant S and NB

Quasiparticle-QGP / resonance HG equation of state Cylindrical expansion

Parameters fitted to Final flow velocities Hadro-chemistry

Consistency with Chemistry Hydrodynamics Dilepton yields

In-Medium Effects - II

High ET Effects in NA50

Transverse energy fluctuations at b=0

[Capella, Ferreiro & Kaidalov ’00] [Blaizot, Dinh & Ollitrault ’00]

ET > 100 GeV

Extra suppression Minimum Bias analysis

[Capella, Kaidalov & Sousa ’01] Trigger energy loss ?

Other QGP Suppression Mechanisms

Minimum Bias Analysis

Dilepton Spectra