J/ y Dissociation cross section in Vacuum and QGP

1. J/y Dissociation cross section in Vacuum and QGP Su Houng Lee Yonsei University Seoul , Korea • Introduction on dissociation cross section in different models • Progress in QCD calculations: LO and NLO • Dissociation due to thermal gluons and quarks

2. Quarkonium Haron interaction in QCD Important because a) J/y suppression is a signature of QGP in Heavy Ion collision b) J/y suppression can occur through dissociation by hadrons in later stages of HIC, need to know J/y –hadron cross section c) Recent lattice show J/y will survive in QGP up to 2 T_c. need to know J/y –parton cross section

3. 2 1 3 J/y hadron cross section mb 1. Effective model s1/2 (GeV) 2. Quark exchange model 3. LO pert QCD

4. Progressin QCD calculations LO and NLO

5. Basics in Heavy Quark system 1. Heavy quark propagation Perturbative treatment are possible because

6. 2. System with two heavy quarks Perturbative treatment are possible when

7. Perturbative treatment are possible when

8. Historical perspective on Quarkonium Haron interaction in QCD • Peskin (79), Bhanot and Peskin (79) • a) From OPE • b) Binding energy= e0 >> L • Kharzeev and Satz (94,96) , Arleo et.al.(02,04) • a) Rederive, target mass correction • b) Application to J/y physics in HIC

9. Rederivation of Peskin formula using Bethe-Salpeter equation (Lee,Oh 02) Resum Bound state by Bethe-Salpeter Equation

10. 2. External interaction: OPE NR Power counting in Heavy bound state 1. Perturbative part

11. LO Amplitude

12. 2 1 3 However, near threshold, LO result is expected to have large correction

13. NLO Amplitude

14. q1 NLO Amplitude : Collinear divergence when q1=0. Cured by mass factroization

15. q1 Integration of transverse momentum from zero to scale Q Mass factorization Gluons whose kcos q1 < Q scale, should be included in parton distribution function

16. NLO Amplitude : Higher order in g counting

17. Application to Upsilon dissociation cross section Fit quark mass and coupling from fitting to coulomb bound state gives

18. Total cross section for Upsilon by nucleon: NLO vs LO NLO NLO/LO LO Large higher order corrections Even larger correction for charmonium

19. Thermal quark and gluon masses of 300 MeV will Reduce the large correction What do we learn from NLO calculation ? 1. Large NLO correction near threshold, due to log terms 2. Dissociation by quarks are less than 10% of that by gluons << Quenched lattice results at finite temperature are reliable

20. Total cross section: gluon vs quark effects With thermal mq = mg = 200 MeV

21. Effective Thermal cross section: gluon vs quark effects

22. Effective Thermal width: gluon vs quark effects

23. Summary • We reported on the QCD NLO Quarkonium-hadron dissociation cross section.  Large correction even for upsilon system, especially near threshold 2. The corrections becomes smaller with thermal quark and gluon mass of larger than 200 MeV  The thermal widht of J/y becomes 1 GeV at T=600 MeV 3. The dissociation cross section due to quarks are less than 10 % of that due to the gluons.  The quenched lattice calculation of the mass and width of J/y at finite temperature should be reliable.

24. q2 = 0  photo production of Open charm: expansion paramter = Example LO QCD Total cross section for open charm CM energy Meson exchange model Wei, Ko, Lee (03)

25. Extraction from pA data by He, Hufner and Kopeliovich (01) LO ressult for y –gluon, y’-gluon dissociation (Oh, Kim, Lee (02)) LO ressult for y –nucleon, y’-nucleon dissociation (Oh, Kim, Lee (02))