charm hadron production at rhic in combination model motivation quark combination model results and...
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Charm hadron production at RHIC in combination model
• Motivation
• Quark combination model
• Results and discussions
• Summary
2008-9-20 JiNan China
Tao Yao, Wei Zhou, Qu-Bing XieSchool of Physics, Shandong University
• One of the hot topics of both theory and experiment . * many theory papers: the charm flow, energy loss, production etc. * PHENIX and STAR collaborations have made many measurements. ◆ the binary scaling of ; STAR gives ~2 times bigger than PHENIX !
Two key ratios: ;
• The effects on charm hadron ratios from the baryon and strangeness enhancements are studied and predictions for RHIC and LHC are given.
• Important to accurately measure in future.• The hadronization mechanism can be tested at RHIC and LHC.
I. Motivation
baryon enhancement
coalescence mechanism
charm baryon enhancement
different charm hadron ratios
different, /e cc
R 0 /D ccR effects on NN
cc
NN
cc
?
NN
cc
cc/ ( ) / 2
/e cc cce eR N N
0 00/ ( )/2/
ccD cc D DR N N
/J
The two ratios used in AA are now from reactions or annihilations)( ppp ee
II. Quark Combination Model (QCM) in AA
( ) (2 1) iri i i sC M J
( ) iri i sC B
( )M qq
( )B qqq
(4)fSU
quark new netN N N ( ), ( )Tf y f P: : : 1:1: :s c s cu d
N N N N
Nearest in rapidity axis Collinear
DecayPYTHIA6.4
F.L.Shao et al. P. R. C71, 044903, 2005 ; P. R.C75,034904,2007.
Rapidity and distribution
Tp
Final hadrons
Tp��������������
130 GeV: =0.75 mb, =41 mb, =965 (0-5%), 1862.4 GeV: =0.285mb, =36 mb, =904.3(0-5%), 7
5.5 TeV: =20 mb, =60 mb, =1303(0-10%), 343
• The number of pairs , as input in the QCM, is given by
The spectrum of charm quark at 200 GeV is inputted as a normalize
d form 354.0)185.31()( 7.22 TTc ppf
(1)NN ppbin inelcc cc
N N
NN
cc
NN
cc
ccNpp
inel binNNN
cc
ccN
200 GeV STAR: =1.4 mb, =42 mb, =1051(0-5%), 35PHENIX: =0.622 mb, 16
NN
cc
ccNpp
inel binNNN
cc
ccN
ppinelppinel
binN
binN cc
N
ccNcc
,3cc PV 5.0cc OD
III. Results and discussions
Fig.1. The invariant spectra at 200 GeV for meson, inclusive electron, non-photonic electron and muon. The solid (dashed) line are from the by the STAR (PHENIX) coll.
TP
A. dependencies of charm baryon to meson ratios and orderingTP
AAR
Fig. 2. The dependence for the ratios of charm baryons to mesons at 200 GeV
TP
The charm baryon enhancement is very
prominent.
The shapes are dependent on the CO/RE mechanism,
decay effect and the charm quark spectrum
All peaks broaden and shift right essentially because the spectrum of charm quark is much harder than that of
u(d) quark
A very similar of nonphotonic muon to that of no
nphotonic electron
AAR
The ordering with strangeness content for strange hadrons has been
observed at RHIC
Nucl.Phys.A774:657-660,2006. STAR
AAR
The effect should also be manifested by the strange charm hadrons.
A powerful signal to prove the CO/RE hadronization mechanism for open ch
arm hadrons.
~67.7%
~100%
~32.3%
1. Strangeness enhancement48.0s
2. Branching ratios
3. Default 3cc PV
But is used by PHENIX
if 5.1cc PV
81.0 DDs
1 DDs
B. The ratios in AA collisions at 200 GeV
Assuming and
PHENIX has , whereas we have
~12% enhancement of !
The newest branching ratio for
from PDGlive, give
~17% enhancement of !NN
cc
(2)
NN
cc
%)4.00.16(%17.053.6
%10.8 99.084.0/
cceR
is
charm decuplet baryons charm octet baryons
~100%
2. the parameter dependence: almost independentc cD O
3. the parameter dependences
independent of !s
/,
e ccR / cc
R
4. the parameter dependenceddN N
Note that the net baryon number or the u(d) quark number decreases with increasing:dd
N N
a.
b.
c.
d.
decrease with ddN N
u
u
D
D
u
d
D
D~,~
0
00
decreases (increases) for the net baryon number decreases.)( 00 DD cc
are independent of ddN N
u
s
D
Dand
u
s
D
D
u
d
D
D ss ~~,~000
and are also independent of the net baryon number./,
e ccR 0 /D cc
R/ cc
R
Fig.3. The data and solid line are the same as Fig. 1, but the dashed line is from the input , the solid line is from .
88.0)185.31()( 12 TTc ppf
354.0)185.31()( 7.22 TTc ppf
Important for us to study their centrality dependence neglecting
the differences of radial flows
Important to study these ratios atvarious energies without the quark
spectra being well determinedTp
5. the c quark spectrum dependence: insensitive Tp
Fig. 4. The centrality dependence for rapidity density of charm hadrons at 200 GeV
cH binccM N N
NN ppbin inelcc cc
N N +
4/3bin partN N
+
.cH
bin
dMconst
N dy
1/3cHpart
part
dMN
N dy
consistent qualitatively with that of the Statistic Hadronization Model: P. L. B 571, 36 (2003)
D. the centrality dependence
yield of single-charm hadron
cHM
' / / ' / / ' / /(3)
/ / / / / /c c c
c
c c c
H part H bin H ccH
H part H bin H cc
dM dy N dM dy N dM dy NR
dM dy N dM dy N dM dy N
D. The centrality dependence of the ratios
They are all independent of the centrality or !NN
cc
Then within coalescence/recombination framework
cH binccM N N
Assuming parameters are independent of the centrality
Note that Eq. (3) is still valid at different energy !Important for us to study the ratios at different energy, especially at LHC energy for large uncertainty of !
E. The energy dependence of the ratios
c cD Oc cV P
QC
M
the coalescence/recombination mechanism
the parameters ,
hadronizationmechanism
universal in AA
the strangeness suppression factor
the net baryon number
factors vary with energy
ratios variance with energy
NN
cc
= 0.52, 0.48, 0.48, 0.48 = 0.859, 0.915, 0.927, 0.986(0.995)
Sdd
N N62.4, 130, 200 GeV RHIC
5500 GeV LHC
Predictions for RHIC and LHC in Table I
• The predictions of dependencies for the charm ratios , and are given. The charm baryon enhancement in intermediate range,
similar to that of ratio, is very prominent.
• ordering with strangeness content for charm hadrons are discussed.
• The ratios in AA collisions are apparently different from those in reactions or annihilations due to the charm baryon enhancement and the strangeness enhancement, along with the newest decay data from PDG, the measured by PHENIX will become larger up to ~17%.
• The dependencies on energy, centrality and various parameters are studied.
• Predictions of charm hadron ratios for the upgrade of RHIC and for LHC are given. They are important for precise measurement of in future and the hadronization mechanism for open charm hadrons can be tested.
Summary
Thank you all !
NN
cc
NN
cc
Tp
( )pp pee
/p
00 DD
cc
DDcc
ss
cc
DD Tp
AAR
Details in arXiv: 0809.0049
The invariant spectra for SU(3) mesons (left panel) and baryons (right panel) in top centrality at 200GeV.
TP
The invariant spectra for proton(left panel) and pion (right panel) at different centrality classes at 200 GeV
TP