Heavy-Quark Diffusion, Flow and Recombination at RHIC

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Heavy-Quark Diffusion, Flow and Recombination at
RHIC
Ralf Rapp Cyclotron Institute Physics
Department Texas AM University College
Station, USA With H. van Hees, V. Greco
() Strangeness in Quark Matter Conference 2006
Los Angeles, 30.03.06
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1.) Introduction-I The Virtue of HQs in URHICs

• , production follows
• N-N collision-scaling
• ? Valuable Probe of Medium

PHENIX 04

• distinguishable from gluons
• mass charge-dependence of jet quenching
  (induced radiation?)
• elastic rescattering, (approach to)
  thermalization, collective flow
• pQCD?! sQGP?!
• coalescence at low(er) pT
• cq? D (even in pp), cc ? Y

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1.2 Intro-II pQCD Jet Quenching
Armesto et al 05
Gyulassy et al 05
Challenges

• enough quenching? (upscaled transport
  coefficient)
• Gluon Plasma (maximal color charge)
• pions over-quenched (pT 4GeV)
• drag on heavy quarks ? flow
• consistency v2 ? RAA

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1.3 Intro-III Single-e Elliptic Flow
?
Armesto et al 05
jet-quench Djordjevic et al 04
coalescence assuming v2cv2q vs.
jet quenching
Challenges

• dynamical origin of re-interactions
• radiative vs. elastic scattering, 3?3
• bottom contribution
• transition soft intermediate - hard

LiuKo06
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Outline
2.) Baseline Spectra in p-p, d-Au Charm
vs. Bottom 3.) Heavy-Quark Elastic Scattering in
QGP Brownian Motion and Thermal
Relaxation pQCD vs. Resonances 4.)
Heavy-Quark and Electron Spectra at RHIC
Langevin Simulation, Hadronization RAA and
v2 5.) Heavy Quarkonia Charmonium
pT-Spectra 6.) Summary
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2.) Heavy-Flavor Baseline Spectra at RHIC
Semileptonic Electrons
D-Mesons

• bottom crossing at 5GeV !? (pQCD Cacciari et
  al 05)
• strategy fix charm with D-mesons, adjust bottom
  in e-spectra

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3.) Heavy-Quark Elastic Scattering in the QGP

• Brownian
• Motion

Fokker Planck Eq.
Svetitsky 88,
Q
scattering rate diffusion constant
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3.2 Open-Charm Resonances in QGP
Light-Quark Resonances
van Hees RR 04
1.4Tc

• effective model with pseudo/scalar
• axial/vector D-mesons

Asakawa Hatsuda 03

• parameters mD2GeV , GD ,
• mc1.5GeV, mq0
  

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3.3 Heavy-Quark Thermalization Times in QGP
Charm pQCD vs. Resonances
pQCD
D

• decreased by factor 3
• with resonances

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4.) Heavy-Quark and Electron Spectra at RHIC 4.1
Relativistic Langevin Simulations for HQs

• initialize heavy quarks (Glauber) in elliptic
  QGP fireball
• realistic time evolution of bulk v0 , v2
• simulate HQ paths with drag and diffusion in QGP

van Hees, GrecoRR 05
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4.2.1 Single-e at RHIC Effect of Resonances

• hadronize output from Langevin HQs (d-fct.
  fragmentation, coalescence)
• semileptonic decays D, B ? enX

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4.2.2 Single-e at RHIC Resonances Q-q
Coalescence
fq from p, K
Greco et al 03
Elliptic Flow
Nuclear Modification Factor

• less suppression and more v2 for pT 1-5 GeV
• anti-correlation RAA ? v2 from coalescence
  (both up)
• radiative E-loss at pT 5GeV ?!

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4.2.3 Formfactor Effect on Resonance Formation

• replace (renormalized) point
• vertex by formfactor (L1GeV)

Charm-Quark RAA
Charm-Quark v2

• formfactor affects higher pT
• rather far from equilibrium

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5.) J/y pT-Spectra in Au-Au at RHIC

• Recombination via Quark Coalescence at Tc

Zero vs. Maximal Reinteraction Realistic
Input from Langevin
pQCD scatt.
resonance scatt.
Greco,van HeesRR in prep

• total yields different by up to factor 3
• rather sensitive to radial flow
  (bt,max0.5-0.65)
• Cronin effect for quantitative RAA

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6.) Summary

• D-/B- resonances in sQGP (elastic
  scattering)
• - accelerate c-/b-quark thermalization
  (factor 3 over pQCD)
• - coalescence increases both v2 and RAA
  (consistency!)

• existence of resonances (q-Q, q-q) to be
  scrutinized
• complete treatment incl. elastic radiative
  processes
• - discriminate with angular correlations
  (tagged Q-jets)?

• pQCD energy loss ? Gluon-Plasma, color charge
• resonances ? Quark-Gluon Plasma, nonpert.
  dynamics

• consistency with / impact on - light-parton
  spectra
• 
  - quarkonia (v2!)
• 
  - IM dileptons (vs. QGP radiation)

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2.4.1 Langevin-Simul. at RHIC Heavy-Quark RAA
Resonances vs. pQCD
Charm-pQCD (as, mD1.5T)
as , g 1 , 3.5 0.5 , 2.5 0.25,1.8

• hydro with Tc165MeV, t 9fm/c
• as and Debye mass independent

• expanding fireball hydro
• pQCD elastic scatt. moderate
• resonance effects substantial

Moore and Teaney 04
van Hees,GrecoRR 05
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4.1.2 HQ Langevin-Simulations with Hydro pQCD

• Charm-pQCD cross sections with variable as ,
  mD1.5T fix
• Hydrodynamic bulk evolution with Tc165MeV, t
  9fm/c

Elliptic Flow
Nuclear Modification
as , g 1 , 3.5 0.5 , 2.5 0.25,1.8

• correlation small RAA ? large v2
• realistic coupling / decoupling ?

MooreTeaney 04
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4.2.3 Semi-Central e RAA at RHIC

• Elliptic QGP fireball with D-/B-resonances,
  coal./frag. and decay

Fragmentation only
Coal. Frag.

• coalescence favored

van Hees,Greco RR 05
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4.2.3 Light-Parton Jet-Quenching RHIC

• pion quenching in pQCD

Armesto et al.

• problems below 4-5GeV

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3.4.3 Scrutinizing Charmonium Regeneration II
J/y Elliptic Flow
Suppression only
Thermal Coalescence at Tc
Greco etal 04
WangYuan 02
MB Au-Au

• factor 5 different!
• transition in pt!?

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5.) Resonances in QGP from Lattice QCD
_
Lattice Q-Q Free Energy
Bielefeld Group 04
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5.2 Lattice Spectral Functions vs. T-Matrix in
QGP
_
LQCD Spectral Function Charmonium
Q-Q T-Matrix (ladder approx.) based on Lattice
Potential
Datta etal 03
MannarelliRR 05

• reasonable qualitative agreement

? Evidence for Resonances in sQGP!? more
studies required
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4.3 Single-e at RHIC Transport Calculations
MPC, AMPT

• Parton Cascade with fixed s(q,g-c),
  forward/isotropic, coalescence

Elliptic Flow
pT-Spectra

• similar to Langevin Xsection effect on
  pT-spectra moderate
• no bottom

Zhang,ChenKo 05
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c-Quark Drag and Diffusion Coefficients in QGP

van HeesRR 04
Thermalization Times
pQCD
D

• substantially smaller for
• resonances

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4.4 Charmonium in A-A
SPS
RHIC
Pb(158AGeV)-Pb

• QGP-suppression prevalent
• no jump in theory

Grandchamp etal. 03