Charm hadron production at RHIC studied in combination model

• Motivation

• Quark combination model

• Results and discussions

• Summary

2008-7 HeFei China

Tao Yao, Wei Zhou, Qu-Bing XieDepartment of Physics, Shandong University

Motivation• 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: ;

• Predictions for the upgrade of RHIC and for LHC• Important to accurately measure in future.• The hadronization mechanism can be tested at RHIC and LHC.

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 e

R N N 0 00/ ( )/2

/ccD cc D D

R N N

/J

The charm hadron ratios are hardly measurable directly now in experiments

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

Results and discussions

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, =1065.4(0-5%), 36PHENIX: =0.622 mb, 16

NN

cc

ccNpp

inel binNNN

cc

ccN

ppinelppinel

binN

binN cc

N

ccNcc

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

Fig. 2. The dependence for the ratios of charm baryons to mesons at 200 GeV

TP

~67.7%

~100%

~32.3%

at 200 GeV:

=8.33%

Assuming and

PHENIX has , whereas, we have

~12% enhancement of !

The newest data of decay branch ratio forare from PDGlive, give

~17% enhancement of !NN

cc

(2)

(3) ~ 2% difference of NN

cc

NN

cc

cceR

/

~67.7%

~32.3%

1. the parameter dependencec cV P

The dependences of some parameters for charm hadron ratios

charm decuplet baryons charm octet baryons

~100%

2. the parameter dependence: almost independentc cD O

3. the parameter dependences

4. the parameter dependenceddN N

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: not sensitive Tp

Fig. 4. The centrality dependence for rapidity density of charm hadrons at 200 GeV

open binccN N N

NN ppbin inelcc cc

N N ＋

4/3bin partN N

＋

.open

bin

dNconst

N dy

1/3openpart

part

dNN

N dy

consistent qualitatively with that of the Statistic Hadronization Model: P. L. B 571, 36 (2003)

6. the centrality dependence

' ' '/ / / / / /(4)

/ / / / / /open part open bin open cc

openopen part open bin open cc

dN dy N dN dy N dN dy NR

dN dy N dN dy N dN dy N

The centrality dependence for open charm hadron ratios

They are all independent of the centrality or !NN

cc

Then within coalescence/recombination framework

open binccN N N

7. The energy dependence for open charm hadron ratios

Note that Eq. (4) is still valid at different energy !Important for us to study the ratios at different energy, especially at LHC energy for large uncertainty of !

c cD Oc cV P

QC

M

the coalescence/recombination mechanism

the parameters ,

hadronizationmechanism

universal in AA

the strange suppress 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 LHC

• 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.

• The ratios in AA collisions are apparently different from those in reactions or annihilations, along with the newest decay data from PDG, the measured by PHENIX coll. will become larger up to ~17%.

• Systematically studied the dependencies of various parameters.

• 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

DD

cc

ss

cc

DD Tp

Back up

Zhangbu Xu J.Phys.G32:S309-S316,2006

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

The invariant spectra for inclusive and non-photonic electron at 130 GeV