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