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

~67.7%

~32.3%

1. the parameter dependencec cV P

C. Parameter dependences of the ratios

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

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