1. 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 Xie Department of Physics, Shandong University

2. 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, effects on ？ The charm hadron ratios are hardly measurable directly now in experiments

3. Quark Combination Model (QCM) in AA Nearest in rapidity axis Collinear Decay PYTHIA6.4 F.L.Shao et al. P. R. C71, 044903, 2005 ; P. R.C75,034904,2007. Rapidity and distribution Final hadrons

4. 130 GeV: =0.75 mb, =41 mb, =965 (0-5%), 18 62.4 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 normalized form Results and discussions 200 GeV STAR: =1.4 mb, =42 mb, =1065.4(0-5%), 36 PHENIX: =0.622 mb, 16

5. 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.

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

7. ~67.7% ~100% ~32.3% at 200 GeV:

8. =8.33% Assuming and PHENIX has, whereas, we have ~12% enhancement of ! The newest data of decay branch ratio for arefrom PDGlive, give ~17% enhancement of ! (2) (3) ~ 2% difference of

9. ~67.7% ~32.3% 1. the parameter dependence The dependences of some parameters for charm hadron ratios

10. charm decuplet baryons charm octet baryons ~ 100 % 2. the parameter dependence: almost independent 3. the parameter dependence

11. 4. the parameter dependence

12. 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. Important for us to study their centrality dependence neglecting the differences of radial flows Important to study these ratios at various energies without the quark spectra being well determined 5. the c quark spectrum dependence: not sensitive

13. Fig. 4. The centrality dependence for rapidity density of charm hadrons at 200 GeV ＋ ＋ consistent qualitatively with that of the Statistic Hadronization Model: P. L. B 571, 36 (2003) 6. the centrality dependence

14. The centrality dependence for open charm hadron ratios They are all independent of the centrality or ! Then within coalescence/recombination framework

15. 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 ! QCM the coalescence/ recombination mechanism the parameters, hadronization mechanism universal in AA the strange suppress factor the net baryon number factors vary with energy ratios variance with energy = 0.52, 0.48, 0.48, 0.48 = 0.859, 0.915, 0.927, 0.986(0.995) 62.4, 130, 200 GeV RHIC 5500 GeV LHC

16. Predictions for LHC

17. 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 !

18. Back up

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

20. The invariant spectra for SU(3) mesons (left panel) and baryons (right panel) in top centrality at 200GeV.

21. The invariant spectra for proton(left panel) and pion (right panel) at different centrality classes at 200 GeV

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