an tai aug.9-14, 2004, ccast workshop, beijing 1 open charm and charmonium production at rhic (1)...
DESCRIPTION
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 3 Geometry of Nucleus-Nucleus Collisions N part – No of participant nucleons N binary – No of binary nucleon-nucleon collisionsTRANSCRIPT
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 1
Open charm and charmonium production at RHIC
(1) Motivations(2) Results from STAR and PHENIX(3) Conclusions and outlook
An Tai
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 2
J/D
K*Kpd, HBT
vv22 saturatessaturates
TT saturatessaturates
Q2
time
Heavy flavor probing the matter properties at early stage in heavy ion collisions, gluon structure function in nucleus.
1410*3.2
)2.0
5.0*5.05.1*5.114.3(
)exp(22
sc mmtorpenaltyfac
J/ψ( ) D( )
mc=1.2-1.5 GeV/c2
uccc
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 3
Geometry of Nucleus-Nucleus Collisions
Number of Participants
Impact Parameter
Npart – No of participant nucleonsNbinary – No of binary nucleon-nucleon collisions
pddnN
pddn
pddAB
pdd
pp
binary
AB
D
J
ppAB
33
/
33
1
93.0
)(
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 4
Heavy flavor production is a crucial probe of a QGP
TrV Dreq Dr /1,)( /
4
J/psi dissociation in QGP ?
QGP
Debye Screening
D < Size of J/ψ, a bound state can not exist J/ψ suppression
ccc
ccc
cc
However, J/ψ may be formed through coalescence at RHIC J/ψ enhancement
! New lattice QCDJ/ψ survives up to 1.6 Tc
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 5
c-quark energy loss testing the dead-cone effect
M. Djordjevic and M. Gyulassy QM04
D. Kharzeev, PLB 519 (2001) 199-206
Another stringent test of jet energy loss in a QGP
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 6
Is the charm quark hadronization modified by the thermal medium ?
StatisticalCalescene Model
0.229
0.504
0.190
0.075
0.214
Statistical model: A. Andronic etc. nucl-th/0209035 and private communication
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 7
STAR --- TPC, TOF, EMCal -- large acceptancePHENIX--- Drift chamber, RICH, EMCal, two-arm muon detector -- small acceptance, high rate capability
pp, dAu, AuAu, √s=130 GeV,200 GeV
PHENIX
4.2||2.1:
35.0||:
e STAR
1||:,,, pKe
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 8
(9.1%)
we also measure D from its semi-leptonic decay to electrons, D eX
KD
%)8.3(%),68( 00* KDDD s
)(00 KD
%)8.3(0 KD
Decay channels used to construct open charm
(6.2%)
About 15 M dAu minbias events are used in the analysis
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 9
Mass plots from dAu data using event-mixing technique
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 10
Results--- D spectrum and Ratios
Open symbol D+/D0Solid symbol D*/D0
dAu minbias at √s=200 GeV
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 11
Phenix measured open charm through D eX at √s=130 and 200 GeV in Au+Au collisions
NNcc
NNcc
NNcc
central
peripheral
No significant charm enhancement in Au+Au over pp binary scaling is observed for pT(D)>1 GeV/c
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 12
A combined fit using D0 and the electron data leads =1.44± 0.20 ± 0.44 mb
Compare measurements of open charms with background-subtracted electron data in STAR
NNcc
The band is obtained from D decay based on the power-law fit to the measured open charm spectrum.
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 13
pQCD calculations of charm cross section
LO
NLO
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 14
Charm cross section vs NLO calculations
PHENIX and STAR data are consistent within uncertainties.
STAR measured charm cross section is higher than the NLO predictions by factor of 3-5.
cc=709b±85(stat) (sys)+332
-281
√s=130 GeV
cc=420b±33(stat)±250(sys)
√s=200 GeV
STAR
cc=1400b±200(stat)±400 (sys)
PHENIX
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 15
Fragmentation of a c-quark
γp
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 16
Is the fragmentation function universal ? Bare c-quark distribution from NLO coincides with D spectrum ---- Peterson’s
Function is too soft for charm hadronization in hadron-hadron collisions.
π+A scattering
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 17
Charm quark hadronization at RHIC
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 18
PHENIX: J/e+e- and +- from pp
pT and rapidity shape are consistent with COM over phenix coverage.
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 19
Cross section and <pT> from pp
= 3.99 +/- 0.61(stat) +/- 0.58(sys) +/- 0.40(abs) b <pT>=1.80+0.23(stat.)+0.16(syst.
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 20
Predicted Gluon Shadowing in d+Au
J/ in dAu collisions at RHIC
From Eskola, Kolhinen, VogtNucl. Phys. A696 (2001) 729-746.
d Au
x
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 21
J/ψ production via coalescence ?
R. L. Thews, M. Schroedter, J. Rafelski, Phys Rev C 63, 054905Plasma Coalescence Model
Binary Scaling
Absorption (Nuclear + QGP) + final-state coalescence
Absorption (Nuclear + QGP)L. Grandchamp, R. Rapp, Nucl Phys A709, 415; Phys Lett B 523, 60
PHENIX
Disfavor models with enhancement over binary collision scaling.
Ncc ~ 7 in central Au+Au, may be possible.cc
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 22
Conclusions Open charm and J/ψ are measured at RHIC in pp, dAu and
Au+Au collisions. =0.709-1.4 mb, σNNJ/ψ=3.99 +/-
0.61(stat) +/- 0.58(sys) +/- 0.40(abs) µb. The STAR measured charm cross section for NN collisions
is larger than the NLO predictions. No significant charm enhancement is observed in AuAu collisions.
The measured D pt spectrum shape coincides with the bare-quark distribution from the NLO calculation.
The measured J/ψ pT and rapidity distributions are consistent with Color Octet Model.
NNcc
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 23
(1) Test dead-cone effect of open charm energy loss, we need to measure RAA (Rcp) with an experimental uncertainty under 20%
(2) v2 measurement of open charm in AA is also difficult due to large combinatorial background
(3) Test charm thermalization, need to measure DsKKπ
Detector upgrade is essential !
Challenge and solution of STAR open charm study in heavy ion collisions
Outlook
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 24
TOF upgrade will greatly enhance STAR open charm study by providing better particle identification
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 25
STAR Vertex Detector will provide precision needed for our physics goals
Two layers 1.5 cm radius 4 cm radius
24 ladders 2 cm by 20 cm each < 0.2% X0 to limit multiple scattering ~ 100 Million Pixels
Position resolution < 10 µm, D0 cτ = 124 µm DCA daughter
D0
Decaylength
K-
+
DCA between daughters
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 26
Study heavy flavor with the Vertex detector Goals --- study matter properties created at
RHIC Heavy flavor energy loss
Precise D spectra Charm flow
D v2
Charm thermalization Yield of D+, Ds
+, c+
mVertex allows the same measurement 100 times faster than TPC+SVT
Charm quark must go through a thermalized partonic medium
Yes
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 27
END
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 28
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 29
Charm quark hadronization at RHIC
NLO pQCD predictions are provided by R. Vogt, hep-ph/0203151
bare c-quark spectrum, normalized to measured dn/dy
MRST HO
Peterson’s function ε=0.06
c quark
=4,3,2,1 (GeV)^22Tk
After and fragmentationTk
Higher order pQCD is in need or charm hadronization through fragmentation+recombination (R. Rapp and E. Shuryak hep-ph/0301245 ?
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 30
Mass plots from dAu data using event-mixing technique
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 31
With the 10-20 more data in run4 and future detector upgrade (TOF, new vertex detectors), heavy flavor program will address the many outstanding issues related the matter properties formed at RHIC Heavy flavor energy loss
Precise D spectra Charm flow
Charm thermalization Yield of D+, Ds
+, c+
J/ψ suppression or enhancement
Yes
Outlook
Charm quark must go
through a partonic medium
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 32
Charm quark hadronization at RHIC
bare c-quark spectrum, normalized to measured dn/dy
The measured D pt spectrum shape coincides with the bare-quark distribution from the NLO calculation. Data favor a fragmentation function peaked at x~ 1
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 33
Charm quark hadronization at RHIC
bare c-quark spectrum, normalized to measured dn/dy
MRST HO
Peterson’s function ε=0.06
c quark
=4,3,2,1 (GeV)^22Tk
After and fragmentation
Tk
The measured D pt spectrum shape coincides with the bare-quark distribution from the NLO calculation. Data favor a fragmentation function peaked at x~ 1
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 34
J/ψ production via coalescence ?
R. L. Thews, M. Schroedter, J. Rafelski, Phys Rev C 63, 054905Plasma Coalescence Model
Binary Scaling
Absorption (Nuclear + QGP) + final-state coalescence
Absorption (Nuclear + QGP)L. Grandchamp, R. Rapp, Nucl Phys A709, 415; Phys Lett B 523, 60
PHENIX
Disfavor models with enhancement over binary collision scaling.
Ncc ~ 7 in central Au+Au, may be possible.cc
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 35
Open charm spectrum is hard !
Phenix: Phys. Rev. Lett. 88, 192303(2002)
D. Kharzeev,hep-ph/0310358
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 36
c-quark energy loss and the dead-cone effect
M. Djordjevic and M. Gyulassy QM04
D. Kharzeev, PLB 519 (2001) 199-206
Another stringent test of jet energy loss in a QGP
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 37
ratios -- consistent with other experiments
)/( 0DD
Open symbol D+/D0Solid symbol D*/D0
0* /DD
CDF: hep-ex/0307080
HERA: www-h1.de/h1/www/publications/conf_list.html
e+e-: hep-ph/0312054
Statistical model: A. Andronic etc. nucl-th/0209035 and private communication.
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 38
Fragmentation of a c-quarkγp
Charm hdronization
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 39
Is the fragmentation universal ?
Bare c-quark spectrumTkAfter and fragmentation
ε=0.06 π+A scattering at 350 GeV/c
momentum degradation due to fragmentation can be counter-balanced by initial Tk
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 40
x2~ 0.1
x2~ 0.003
x2~ 0.01
Parton initial state multiple scattering leads to broadening of J/ pT
distribution
Broadening comparable to lower energy (s = 39 GeV in E866)
Cronin Effect: pT broadening )1972( ppdA
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 41
STAR D spectrum and single electron data are consistent
dAu minbias at √s=200 GeV dσcc/dy=0.30±0.04(stat.)±0.09(syst.) mb
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 42
S. Frixione, M. Mangano and P. Nason (hep-ph/9702287) in their summary paper of heavy quark production:
“ We conclude that, when using the central value of the charm mass, mc =1.5 GeV, favored by the total cross section measurements, the theoretical results for the p2
T spectrum can describe the data well, only if a large kT kick is applied to the fragmented curve. Therefore, there seems to be a potential discrepancy between theory and experiments in the p2
T spectrum in charm hadroproduction. From a different point of view, however, the discrepancy may be interpreted as the signal that some of the other theoretical assumptions are not totally sound. For example, the Peterson fragmentation function may not be suitable to describe the hadronization process in hadronic collisions; the data would suggest a function more peaked towards the x≃ 1 region. Moreover, higher-order perturbative corrections may also play a role.”
NLO c-quark XF distribution coincides with open charm XF distribution
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 43
Is the fragmentation universal ?Bare c-quark spectrum
TkAfter and fragmentation
ε=0.06 π+A scattering at 350 GeV/c
momentum degradation due to fragmentation can be counter-balanced by initial Tk
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 44
c-quark energy loss and the dead-cone effect
M. Djordjevic and M. Gyulassy QM04
D. Kharzeev, PLB 519 (2001) 199-206
Another stringent test of jet energy loss in a QGP
An Tai Aug.9-14, 2004, CCAST Workshop, Beijing 45
FONLL and CDF data