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Heavy Quarkonium in Quark-Gluon Plasma

IHEP October 15,2004. Heavy Quarkonium in Quark-Gluon Plasma. Introduction Heavy quarkonium in spectral function analysis Heavy quarkonium in potential model Heavy quarkonium bound states in QGP Cross section for g + J/ ψ  C + C Cross section for C + C  g + J/ ψ

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Heavy Quarkonium in Quark-Gluon Plasma

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  1. IHEP October 15,2004 Heavy Quarkonium in Quark-Gluon Plasma • Introduction • Heavy quarkonium in spectral function analysis • Heavy quarkonium in potential model • Heavy quarkonium bound states in QGP • Cross section for g + J/ψ C + C • Cross section for C + C  g + J/ψ • Conclusions • C.Y.Wong, hep-ph/0408020 Cheuk-Yin Wong (黄卓然) Oak Ridge National Laboratory & University of Tennessee

  2. J/ψ suppression as a signature of QGP • J/ψ suppression as a signature of QGP Matsui & Satz, PLB178, 416 (`86) • J/ψ is bound at T slightly greater than Tc Hansson, Lee, & Zahed, PRD37, 2672 (`88) • J/ψ suppresion by collisions with nucleons Gerschel and Huefner, PLB207, 253 (`88) • J/ψ suppresion by collisions with produced particles Vogt, Gavin, Capella, Wong, Barnes, Swanson,Ko,Lin, Lee,Haglin, Blaschke,…… • J/ψ enhancement by recombination Thews & Rafelski, NPA689, 575 (`02)

  3. J/ψ suppression as a signature of QGP • Lattice gauge results for Fav Digal, Petreczky, Karsch, PRD64 094015 (`01) • Lattice gauge spectral function analysis Asakawa,Hatsuda, PRL92, 012001 (`03), Datta,Karsch,Petreczky, J. Phys. G,S431 (`04) • Lattice gauge calculations of color-singlet Q-Qbar potential Kaczmarek, Karsch, Petreczky, & Zantow, hep-lat/030912 Petreczky & Petrov, hep-lat/0405009 • Heavy quarkonium bound state calculations Wong, PRC65,034902(`02) & J. Phys.G28, 2349 (`02) • J/ψ suppression and recombination Grandchamp, Rapp, and Brown, J. Phys. G30, S1355 (`04) • QGP at T slightly above Tc supports weakly bound meson states Zahed & Shrylak, hep-ph/0307267, hep-ph/0403127

  4. Spectral function analysis

  5. Lattice gauge spectral analyses in the quenched approximation show that the width of J/ψ remains narrow up to T ≤ 1.6 TC P. Petreczky, S. Datta, F. Karsch, and I. Wetzorke, hep-ph/0309012. M. Asakawa, T. Hatsuda, and Y. Nakahara, Nucl. Phys. A715, 863 (03)

  6. Questions: • Are there other independent ways to assess the stability of J/ψ in the quark-gluon plasma? 2 What does the potential model say about the stability of J/ψ? 3. What is the binding energy of J/ ψ? 4. How easy is it to dissociate J/ ψ by gluon collisions? 5. How easy is it to recombine C and C to form J/ ψ in QGP?

  7. Kaczmarek, Karsch, Petreczky, Zantow calculated the color-singlet C-C potential in the quenched approximation [hep-lat/0309121] V1(r,T) was calculated in the Coulomb gauge V1

  8. We parameterize the color-singlet Q-Q potential as a screened color-Coulomb potential

  9. Probable reasons for strong coupling αeff(T) just above Tc • Density of gluons increases substantially above Tc • Gluons have a spin (in color space) • Spin response is paramagnetic ---- a spin (in color space) tends to align with the imposed color magnetic field, in such a way to enhance the imposed field • This enhancement leads to anti-screening • There is a competition between anti-screening and dis-alignment due to thermal motion • Magnetic anti-screening wins at T slightly greater than Tc • Magnetic anti-screening wins at large T Therefore, there is a strong coupling αs(T) just above Tc. and αs(T) decreases as T increases.

  10. Solve for Q-Q bound states

  11. Solve for Q-Q bound states

  12. Dissociation temperatures in quenched QCD

  13. Why different dissociation temperatures? • Potential model gives the spontaneous dissociation temperature • Heavy quarkonium can dissociate even before reaching spontaneous dissociation temperature by collision with gluons • Spectral analysis includes the interaction of gluons with heavy quarkonium

  14. Quarkonium dissociation process in the potential model

  15. J/ψ dissociation cross section g + J/ψ → c + c

  16. Average dissociation cross section and dissociation width Γdis

  17. Cross section for production of J/ψby collision of C and C

  18. Rate of J/ψ production

  19. Conclusion • Just above TC, J/ψ and Υ are strongly bound, probably as a result of anti-screening due to free gluons • In the potential model, J/ψ dissociates spontaneously at about 2TC • Below T=2TC, J/ψ dissociates by collision with gluons.. Its collision dissociation width is equal to its binding energy at T=1.2TC • The potential model and the spectral analysis are qualitatively consistent with each other

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