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Comments on J/ y dissociation by partons Progress in QCD calculations: LO and NLO

J/ y hadron interaction in vacuum and in QGP. Su Houng Lee Yonsei Univ., Korea. Comments on J/ y dissociation by partons Progress in QCD calculations: LO and NLO 3. Dissociation due to thermal gluons and quarks.

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Comments on J/ y dissociation by partons Progress in QCD calculations: LO and NLO

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  1. J/y hadron interaction in vacuum and in QGP Su Houng Lee Yonsei Univ., Korea • Comments on J/y dissociation by partons • Progress in QCD calculations: LO andNLO • 3. Dissociation due to thermal gluons and quarks References: Y. Oh, S. Kim, S.H.Lee, (LO) : PRC 65 (2002) 067901 Taesoo Song, S.H.Lee, (NLO) : PRD 72 (2005) 034002 Y. Park, K. Kim, T. Song, K. Ohnishi, K. Morita S.H.Lee …

  2. J/y suppression in Heavy Ion collision • 1. 1986: Matsui and Satz J/y suppression • Nuclear and comover suppression • SPS data SPS data 4. Thermal enhancement 5. Lattice shows J/Y survives up to 1.6 Tc (Asakawa, Hatsuda .. ) 6. Preliminary RHIC data RHIC data

  3. Relevant questions and steps in J/y suppression  Calculate J/y dissociation cross section by partons c c c c • c c are produced by hard collision • Tinitial > 300 MeV in RHIC • As systems cools, J/Y is formed at 1.6 Tc • Dissociation effects until Tc ? • Suppression in hadronic phase …

  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. NR Power counting in Heavy bound state Quarkonium Hadron interaction in QCD - LO • Peskin (79), Bhanot and Peskin (79) • Kharzeev and Satz (94,96) , Arleo et.al.(02,04) • Y.Oh, SHL (02) Rederived using Bethe-Salpeter amplitude (02)

  9. LO Amplitude

  10. Exp data from pA Not so large, however, LO QCD result is known to underestimate nucleon absorption cross section Oh, Kim ,SHL 02 s1/2 (GeV)

  11. NLO Amplitude (Song, SHL 05)

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

  13. q1 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

  14. NLO Amplitude :

  15. Total cross section for Upsilon by nucleon: NLO vs LO NLO/LO Large higher order corrections Even larger correction for charmonium T. Song and SHL, PRD 72, 034002 (2006)

  16. Thermal quark and gluon masses of 300 MeV will Reduce the large correction 2. But at finite temperature, thermal masses will regulate the large correction Lessons from NLO calculation 1. Large NLO correction near threshold, due to log terms

  17. Thermal width of J/y LO and NLO

  18. Assume cc bound state above Tc These will be used throughout this work But result is the same when <r2> is fixed 2. C. Y. Wong… : Deby screened potential 0 e (GeV) -0.8 Tc 1.6xTc J/Y wave functions at finite T J/Y Binding energy as a function T

  19. Increasing T LO F+g c+c

  20. Hight T Low T NLO F+q  c+c+q

  21. 4 body decay ? NLO F+g  c+c+g NLO

  22. Result and Summary • Reported on the quarkonium parton dissociation cross section at NLO in QCD  Result depends of wave function or size <r2> 2. We showed that the process q(g)+J/Y c+c+q(g) gives large thermal width (200 MeV) for J/Y from 1.3 to 1.6 Tc  this corresponds to about <s>= 2-3 mb 3. In heavy ion collision, as the initial QGP cools down, J/Y will start forming at 1.6 Tc. However, the dissociation from 3 body decay is very large.  J/y dissociation will become smaller only near Tc

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