Probing Properties of the QCD Medium via Heavy Quark Induced Hadron Correlations. Huan Zhong Huang Department of Physics and Astronomy University of California Los Angeles, CA 90095-1547 June 26-28, 2008: 417. WE-Heraeus-Seminar. Thanks to Gang Wang and Shingo Sakai. Outline.
Probing Properties of the QCD Medium via Heavy Quark Induced Hadron Correlations
Huan Zhong Huang
Department of Physics and Astronomy
University of California
Los Angeles, CA 90095-1547
June 26-28, 2008: 417. WE-Heraeus-Seminar
Thanks to Gang Wang and Shingo Sakai
pT Scales and Physical Processes
Three PT Regions:
-- multi-parton dynamics
coalescence or …)
(constituent quarks ?
from gluons to
constituent quarks? )
B and D contributions to electrons
Non-photonic e RAA
-- energy loss of HQ
B and D
of D and B mesons
X.Y. Lin, hep-ph/0602067
B vs D: contribution to non-photonic e
pT_asso > 0.3 GeV/c
PYTHIA shows significant differences in B&D on the near-side correlations in p+p collisions, and we can fit the experimental data to obtain B/D contribution.
B contribution to non-photonic e in p+p 200GeV
Almost half-half B and D contributions to non-photonic e’s at 6 < pT < 9 GeV/c, and FONLL prediction is consistent with our data within errors.
Bottom Quarks Suffer Energy Loss Too
Phys. Rev. Lett. 98 (2007) 192301
RAA and B/D of non-photonic electrons
p+p 200 GeV
Central 0-5% Au+Au
M.Djordjevic, PLB632, 81 (2006)
Prejudice or Reasonable
Need to measure B/D
in A+A collisions to
determine RAA for B
and C quarks!
Heavy Flavor Trackers
J. Thomas Talk
Empirical Implications for a constant RAA for pT > 6 GeV/c !!
Energy Loss Shifts pp pT to AA pT-DpT
pT > 5 GeV/c
For a power-law function (1+pT/a)-n
a flat RAA DpT/pT constant !
What Physical Processes?
pT > 5 GeV/c
No significant difference in DpT/pT between light hadron and
non-photonic electrons !
DpT/pT ~ 25% in most central collisions !
The physical origin of the N2/3 dependence? Linear Npart not bad either
The centrality dependence of DpT/pTcould be due to
the initial energy density in collisions !
T. Hirano et al, Phys. Rev. C69, 034908 (2004)
ELoss of Partons:
1) Strong dependence
on energy density
2) Rapid decrease of
energy density in
time interval <
show such a scenario
Path-Length Dependence in Soft Particles
3<pTtrig<4GeV/c & 1.0<pTasso<1.5GeV/c 20-60%
= associate - trigger (rad)
Parallel: M. McCumber; O. Catu; H. Pei
A. Feng; O. Barannikova; A. Adare
At low pT region, the medium response to Parton ELoss
-- has path-length dependence
Caution: the current trigger pT is high enough to be in the
dominant parton energy loss domain !
Non-photonic e-h azimuthal correlation
Uncertainty from ZYAM
0 – 20% most central Cu+Cu collisions at 200 GeV :
pTtrig= 3-6 GeV/c; pTasso = 0.15-0.5 GeV/c
Gang Wang (STAR)
Away Side in medium:
How does B/D lose energy? Via conical emission?
After v2 subtraction, the double-hump has a significance of 3~4 sigma. PYTHIA fit has a big chi2.
On the away side, a broad structure or a possible double-hump feature has been observed, even before v2 subtraction.
Precise value of
v2 at pT > 6, 10 GeV/c ?
RAA at pT > 10 GeV/c at RHIC
should RAA approach
unity at higher pT ?
Future measurements will
shed lights on possible
physical scenarios for
parton energy loss
Heavy Quarks will be special
-- Lorentz g dependence
on parton ELoss
on jet-medium interaction
Mach cone formation?
Parton Energy Loss Hadron PT Scale > 5-6 GeV/c
Heavy Quarks (Charm/Bottom) Suffer Energy Loss
-- Need Direct Charm/Bottom Measurement in A+A
Absence of Clear Path-Length Dependence of ELoss
-- Rapid Decrease of Energy Density with
-- Need v2 Measurement at High pT (> 6 GeV/c)
Jet-medium Interaction Induces Correlations in the
Soft Particle Regime – Path-Length Dependent
Possibly for Conic Shape Correlation
Even for Heavy Quark Induced Jet-Medium Int.