1. Motivation for Studying Heavy Quarks
Heavy quark mass are external parameter to QCD.
Sensitive to initial gluon density and gluon distribution.
energy loss feature different from light quarks. Its suppression and the flow capability provide key information on the hot/dense medium properties.
Suppression or enhancement pattern of heavy quarkonium production reveal critical features of the medium.
Cold Nuclear effect (CNM):
Different scaling properties in central and forward rapidity region CGC.
Gluon shadowing, etc D0 K+ l K-
e-/-
e+/+
Heavy quarkonia
Open heavy flavor

2. How the Measurements is done at RHIC
PHENIX
Meson
J/ψ m m
J/ψe e
D0 --> K p
D --> e +X
D --> m +X

3. How the Measurement is done at RHIC
Meson
J/ψ m m
J/ψe e
D0 --> K p
D --> e +X
D --> m +X
STAR
0-80% Au+Au
STAR Preliminary

4. Heavy Quark Energy Loss in the Medium
light K+
Hot/Dense Medium
“dead cone effect”:
gluon radiation suppressed at q < mQ/EQ u
c quark
e-/- c l D0
radiative energy loss
(D. kharzeev, M.Djordjevic et al. )
Hot/Dense Medium u c D0 K+ l
c quark
e-/-
collision energy loss
(Teany, Ralf, Denes et al.) D0 K+ l
e-/-
meson energy loss
c quark u c
Hot/Dense Medium
Ivan, et al

5. Variables to quantify the medium effect
RAA ( or RdA)
5 N-N collisions
“no effect”
No medium effect
Heavy quarks are from Hard collision:
Each collision is separated clearly.
In the absence of any nuclear effect,
Yield(A+A) = yield(p+p)*N(collisions), i.e. scale with number of collisions (Ncoll)
The larger the energy loss
The smaller the RAA

6. How Measurements has been doneK+
e-/-
PHENIX Measurement
Little material to produce background.
different methods l K-
e+/+ D0 l
Open heavy flavor D0 K+ K-
Open heavy flavor p
STAR Measurement
different measurements
lots of material to produce background.

7. Measurements on RAA in Au+Au collisions
STAR hadrons pT> 6 GeV/c
large suppression of charm quark production is observed
D meson probably less suppressed than light hadrons.
Where the bottom show up in the spectrum?

8. Do we Understand the Result?
PHENIX nucl-ex/
STAR nucl-ex/
Radiative Energy Loss with reasonable gluon densities do not explain the observed suppression
Djordjevic, Phys. Lett. B (2006)
Armesto, Phys. Lett. B (2006)
Collisional EL may be significant for heavy quarks
Wicks, nucl-th/
van Hess, Phys. Rev. C (2006)
heavy quarks fragment inside the medium and are suppressed by dissociation?
Adil and Vitev, hep-ph/
Similar suppression for B and D at high-pT

9. Energy Loss and Flow are Closely connectedx y z
Charm was NOT expected to flow with the medium since it’s too heavy !

10. Flow of electrons from Charm and Bottom meson decay
[Phys.Lett. B ]
[PRC72,024906]
[PRC73,034913]
[PRB637,362]
Strong elliptic flow for non-photonic electron
Main source is D meson -> indicate non-zero D v2
Charm v2 also non-zero ?
Bottom sneak in here?

11. Quarkonia Suppression: “smoking gun” for QGP
Physics Letter B Vol.178, no c
Low temperature
Vacuum
J/y
High temperature
High density
(screening effect take place) d d D+ D-
The melting sequence: cc -> Y’ -> J/y -> Upsilon

12. The life of J/y in the medium is very complicated
Observed J/y is a mixture of direct production+feeddown.
All J/y ~ 0.6J/y(Direct) + ~0.3 cc + ~0.1y’
Important to disentangle different component (through upgrade)
Suppression and enhancement in the “cold” nuclear medium
Nuclear Absorption, Gluon shadowing, initial state energy loss, Cronin effect and gluon saturation (CGC)
Hot/dense medium effect
J/y dissociation, i.e. suppression
Recombination from uncorrelated charm pairs
Survival (or not) in the hot/dense medium from lattice calculation c
J/y D+

13. Measurements J/y (in medium) in the world
FNAL:
E772/789/866: p+A
Sqrt(s) = 38.8 GeV
HERA-B:
p+A
Sqrt(s) ~42 GeV
SPS:
NA3, NA38/50/60: p+p, p+A, A+A
Sqrt(s) = 18, 20, 28, 30 GeV
RHIC:
PHENIX/STAR: p+p, p+A, A+A
Sqrt(s) =20, 62, 130, 200 GeV

14. Comparing RHIC to SPS Suppression results
NA50 at SPS (0<y<1)
PHENIX at RHIC (|y|<0.35)
PHENIX at RHIC (1.2<|y|<2.2)
NA50 at SPS (0<y<1)
PHENIX at RHIC (|y|<0.35)
PHENIX at RHIC (1.2<|y|<2.2)
Bar: uncorrelated error
Bracket : correlated error
Global error = 12% and
Global error = 7% are not shown
NA50 (0<y<1)
NA50 at SPS (0<y<1)
PHENIX at RHIC (|y|<0.35)
Bar: uncorrelated error
Bracket : correlated error
Global error = 12% is not shown
NA50 (0<y<1)
NA50 at SPS (0<y<1)
Normalized by NA51 p+p data
with correction based on
Eur. Phys. J. C39 (2005) : 355
NA50 (0<y<1)
One of the key observations for CERN to declare QGP discovery.
After removing the CNM effect, differences start to show-up.
suppression at SPS consistent with the melting of psi’ and chi_c.
Suppression pattern similar in RHIC and SPS.
CNM effect not removed yet.

15. Golden Comparisons
Charm flows. If recombination is correct, J/Psi should also flow.
PHENIX expect to accomplish in run7 with higher luminosity (x3) and better (~sqrt(3.5)) reaction plane resolution.
Yan,Zhuang,Xu
nucl-th/
J/
Single electron from open charm meson
Charm suppression increase at higher pT. If recombination is correct, J/Psi suppression should quadratically increased at higher pT.
Not yet observed in PHENIX up to 5GeV.
What the minimum pT to see the pattern?
Single electron from open charm meson

16. A Direct Way to Measure Heavy Flavor (near future)

17. Heavy Flavor Silicon Tracker Upgrade: the core of RHIC-II heavy flavor program
Purdue High Energy Physics P3MD lab