Heavy Flavor Physics at RHIC
Matthias Grosse Perdekamp
U of Illinois and RIKEN BNL
o Overview
o Selected results from RHIC
“light quark” jet quenching
and elliptic flow
o Energy loss of heavy quarks in media
as tool to study nuclear media formed in
heavy ion collisions.
Heavy Flavor Physics at RHIC
Heavy Flavor Physics at RHIC:
Overview
open heavy flavor production spectroscopy: J/ψ, c , Υ (1s,2s,3s)
QGP?
A-A
1) Energy loss in dense and
hot nuclear matter
2) Tomography of DHNM
3) Reference data for quarkonia
PDF(A)
1)
p/d-A
2)
QCD
p-p, d-A, A-A
Polarized PDFs
p-p
Quarkonia as “Thermometer”:
color screening depends on T
Matsui and Satz, Phy.Lett. B 178 (1986)416
Modification of PDFs in nuclear environment (anti-) shadowing
vs new state of matter (color glass condensate)
Reference data for initial state in A-A
1) Cross sections vs rapidity and √s
2) Vacuum energy loss vs media
3) Reference data
measure
G ( xg )
Heavy Flavor Physics at RHIC
1) Hadronization mechanism
2) Reference data for quarkonia
formation process?
Polarized pp: ΔG from charm production
Double spin asymmetry electron
asymmetry for charm production
Scale dependence reduced at NLO:
(I. Bojak and M. Stratmann, hep-ph/0112276)
e
ALL
xT
LO
xT
Heavy Flavor Physics at RHIC
NLO
Relativistic Heavy Ion Collider
Design Parameters:
Performance
Au + Au
p+p
snn
200 GeV
500 GeV
L [cm-2 s -1 ]
2 x 1026
2 x 1032
Cross-section
7 barns
60 mbarn
Interaction rates 14 kHz
12 MHz
RHIC Capabilities




Au + Au collisions at 200 GeV/u
p + p collisions up to 500 GeV
spin polarized protons (70%)
lots of combinations in species and
energy in between
Heavy Flavor Physics at RHIC
RHIC Running
Delivered 1196 (mb)-1 to Phenix [week ago : 1060]
136 (mb)-1 last week [best week: 158]
2 x design
Luminosity!
maximum
projection
physics target
minimum
projection
Heavy Flavor Physics at RHIC
Charm and J/ψ Data from RHIC
Run I, 2001
Au-Au beams at s=130 GeV
•Open charm from PHENIX
Run II, 2002
Au-Au beams and p-p at s=200 GeV
•Open charm and J/Y from PHENIX
Run III, 2003
d-Au, p-p at s=200 GeV
•Open charm from PHENIX and STAR, J/Y from PHENIX
Run IV, 2004
Au-Au, s=200 GeV
•More measurements to come
Heavy Flavor Physics at RHIC
STAR: Large acceptance TPC+EMC
Heavy Flavor Physics at RHIC
Au-Au Event in STAR
Heavy Flavor Physics at RHIC
PHENIX Physics Capabilities
designed to measure rare probes:
Au-Au & p-p spin
+ high rate capability & granularity
+ good mass resolution and particle ID
- limited acceptance
•
2 central arms:
electrons, photons, hadrons
– charmonium J/, ’ -> e+e– vector meson r, w,  -> e+e– high pT
po, p+, p– direct photons
– open charm
– hadron physics
•
2 muon arms:
muons
– “onium” J/, ’,  -> m+m– vector meson  -> m+m– open charm
•
combined central and muon arms:
charm production
DD -> em
•
global detectors
forward energy and multiplicity
– event characterization
Heavy Flavor Physics at RHIC
Au-Au and d-Au events in the PHENIX Central Arms
Au-Au
d-Au
Heavy Flavor Physics at RHIC
Open charm in pp: Single electrons
charm cross sections (barely) agree!
p+p
d + Au
PHENIX PRELIMINARY
 cNN
c =1.36 ± 0.20 ± 0.39 mb
PHENIX: three methods to subtract
photonic background
STAR: three methods to identify
electrons
Heavy Flavor Physics at RHIC
Consistency between electron data sets
• STAR slightly above PHENIX
Heavy Flavor Physics at RHIC
Does the PYTHIA “extrapolation” work?
PYTHIA tuned to available data (sNN < 63 GeV) prior to RHIC results
1Phys.
Rev. Lett. 88, 192303 (2002)
PHENIX PRELIMINARY
 spectra are harder than PYTHIA extrapolation from low energies
 Use parametrization for Au-Au reference
 Use rapidity dependence from PYTHIA to extract cross section
Heavy Flavor Physics at RHIC
Reconstruction of D mesons in dAu Collisions
0 < pT < 3 GeV/c, |y| < 1.0
d+Au minbias
D0+D0
 cNN
= 1.12 ± 0.20 ± 0.37 mb from D data
c
(1.36 ± 0.20 ± 0.39 mb with electrons)
Heavy Flavor Physics at RHIC
Collision Geometry -- “Centrality”
Spectators
Participants
For a given b,
Glauber model
predicts Npart
(No. participants)
and Nbinary
(No. binary collisions)
15 fm
0
0
b
Npart
Nbinary
0 fm
394
1200
Heavy Flavor Physics at RHIC
Experimental Determination of Centrality
BBC
ZDC
Au
ZDC
Au
BBC
ZDC: zero degree
calorimeter
BBC: beam-beam
counter
Heavy Flavor Physics at RHIC
Selected Results: Elliptic Flow
Origin: spatial anisotropy of the system when created, followed by
multiple scattering of particles in the evolving system
spatial anisotropy  momentum anisotropy
v2: 2nd harmonic Fourier
coefficient in azimuthal
distribution of particles with
respect to the reaction
plane

Almond shape
overlap region
in coordinate
space
Outgoing
particle
v2  cos2
Heavy Flavor Physics at RHIC
  atan
py
px
E. Shuryak
Heavy Flavor Physics at RHIC
Large v2
STAR v2 for charged particles
• Hydrodynamic limit
exhausted at RHIC for low
pT particles.
Adler et al., nucl-ex/0206006
• Large magnitude of v2
suggests highly viscous
“liquid”: strongly interacting
nuclear medium has been
formed!
Heavy Flavor Physics at RHIC
Probing the nuclear medium formed:
Jet Suppression
charm/bottom dynamics
J/Y & 
direct photons
CONTROL
Heavy Flavor Physics at RHIC
Light qs and g jets as probe of the medium
schematic view of jet production
Jets from hard scattered
quarks observed via fast
leading particles or
azimuthal correlations
between the leading
particles
hadrons
leading
particle
q
q
hadrons
leading particle
However, before they create jets, the scattered quarks
radiate energy (~ GeV/fm) in the colored medium
Decreases their momentum (fewer high pT particles)
Eliminates jet partner on other side
Jet Quenching
Heavy Flavor Physics at RHIC
Quantify Nuclear Modification of Hadron Spectra
1. Compare Au+Au to nucleon-nucleon cross sections
2. Compare Au+Au central/peripheral
Nuclear
Modification
Factor:
d 2 N AA / dpT d
RAA ( pT ) 
TAAd 2 NN / dpT d
nucleon-nucleon
cross section
<Nbinary>/inelp+p
AA
AA
AA
If no “effects”:
RAA
< 1 in regime of soft physics
RAA
= 1 at high-pT where hard
scattering dominates
Suppression:
RAA< 1 at high-pT
Heavy Flavor Physics at RHIC
Quantitative Agreement across Experiments
Effect is real…Final or Initial State Effect?
Heavy Flavor Physics at RHIC
Centrality Dependence Au-Au vs d-Au
Au + Au Experiment
Final Data
d + Au Control Experiment
Preliminary Data
• Significantly different and opposite centrality evolution of
Au+Au experiment from d+Au control.
• Jet Suppression is clearly a final state effect.
Heavy Flavor Physics at RHIC
Heavy Quark Energy Loss in Media
1997 Shuryak proposed that charm quarks may suffer a large energy loss
when propagating through a high opacity plasma, leading to large
suppression of D mesons. (E. V. Shuryak, Phys. Rev. C 55, 961 (1997)
2001 Dokshitzer and Kharzeev propose the “dead cone” effect:
Reduced gluon emission at small angles in media for heavy quarks
may lead to enhancement in D meson production.
Y.L. Dokshitzer and D. E. Kharzeev, Phys. Lett. B 519, 199 (2001)
2003 Djordjevic and Gyulassy: detailed quantitative
treatment of heavy quark energy loss in strongly
interacting media. Predict slight suppression: 0.6-0.8!
M. Djordjevic and M. Gyulassy, nucl-th/0310076
Heavy Flavor Physics at RHIC
Radiative heavy quark energy loss
from Magdalena Djordjevic at QM 2004
There are three important medium effects that control the
radiative energy loss at RHIC
1) Ter-Mikayelian effect (Djordjevic-Gyulassy Phys.Rev.C68:034914,2003)
2) Transition rediation (Zakharov)
3) Energy loss due to the interaction with the medium
Ter-Mikayelian:
QCD analog to
dielectric effect
in electrodynamics
1)
2)
Heavy Flavor Physics at RHIC
3)
pp reference
pp reference
1/TAA
1/TABEdN/dp3 [mb GeV-2]
AA
3
-2
1/TABEdN/dp
1/T [mb GeV ]
AA
3 3 GeV
-2] -2]
GeV
1/T1/T
ABEdN/dp
ABEdN/dp
1/T [mb[mb
pp reference
EdN/dp3 [mb GeV-2]
1/T1/T
AA AB
1/TAAABEdN/dp3 [mb GeV-2]
1/T
Centrality dependence in AuAu
pp reference
pp reference
No deviations from binary scaling within uncertainties.
Consistent with Djordjevic and Gyulassy: 10 x more data from Run 2004!
Heavy Flavor Physics at RHIC
Centrality dependence in dAu
PHENIX PRELIMINARY
3
-2
1/T
1/T
ABABEdN/dp [mb GeV ]
PHENIX PRELIMINARY
PHENIX PRELIMINARY
PHENIX PRELIMINARY
3
-2
1/T
ABEdN/dp [mb GeV ]
1/TAB
1/TABEdN/dp3 [mb GeV-2]
1/T
EdN/dp3 [mb GeV-2]
1/T
AB AB
1/TABEdN/dp3 [mb GeV-2]
1/T
AB
PHENIX PRELIMINARY
Single electron spectra in dAu are in good
agreement with the proton reference.
Heavy Flavor Physics at RHIC
Charm flow?
PHENIX PRELIMINARY
•
is partonic flow realized?
•
v2 of non-photonic electrons
indicates non-zero charm flow
in AuAu collisions
•
uncertainties are large
•
definite answer:
RUN-04 AuAu data sample!
Heavy Flavor Physics at RHIC
J/Y: Does colored medium screen cc ?
40-90%
most central
Ncoll=45
20-40%
most central
Ncoll=296
0-20%
most central
Ncoll=779
Statistics limited:
Run 2004!
R.L. Thews, M. Schroedter, J. Rafelski Phys. Rev.
C63 054905 (2001): Plasma coalesence model
for T=400MeV and ycharm=1.0,2.0, 3.0 and 4.0.
Proton
A. Andronic et. Al. Nucl-th/0303036
Heavy Flavor Physics at RHIC
L. Grandchamp, R. Rapp Nucl.
Phys. A&09, 415 (2002) and
Phys. Lett. B 523, 50 (2001):
Nuclear Absorption+ absoption
in a high temperature quark gluon
plasma
Summary
•
The final state produced in central Au-Au collisions at RHIC is dense and opaque and
appears to have the properties of a strongly interaction liquid.
•
The energy loss of heavy quarks in nuclear media is an important tool to further
characterize the nature of the medium produced at RHIC.
•
Heavy flavor production will play an important role in studying nucleon
structure in d-A and polarized p-p collisions at RHIC. The experimental
possibilities will be greatly enhanced by silicon vertex detector upgrades
for PHENIX and STAR.
We expect a significant qualitative and quantitative advance
from run 2004 in understanding the nature of the matter
formed in central collisions at RHIC.
Heavy Flavor Physics at RHIC
PHENIX: J/Ye+e- and m+m- from pp
= 3.99 +/- 0.61(stat) +/- 0.58(sys) +/- 0.40(abs) mb
(BR*tot = 239 nb)
Central and forward rapidity measurements
from Central and Muon Arms:
•Rapidity shape consistent with various PDFs
•√s dependence consistent with various PDFs
with factorization and renormalization scales
chosen to match data
Higher statistics needed to constrain PDFs
Heavy Flavor Physics at RHIC
PHENIX: J/Ye+e- and m+m- from pp
•pT shape consistent with COM over our pT
range
•Higher statistics needed to constrain models at
high pT
•Polarization measurement limited
Heavy Flavor Physics at RHIC