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Quarkonium production and attenuation in high energy pA collisions

Quarkonium production and attenuation in high energy pA collisions. Introduction Quarkonium attenuation Production w/ attenuation Outlook. H. FUJII （ U Tokyo, Komaba). HF, T.Matsui, PLB545, NPA709 HF, F. Gelis, R. Venugopalan, work in progress. Motivations.

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Quarkonium production and attenuation in high energy pA collisions

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  1. Quarkonium production and attenuation in high energy pA collisions • Introduction • Quarkonium attenuation • Production w/ attenuation • Outlook H. FUJII （U Tokyo, Komaba) HF, T.Matsui, PLB545, NPA709 HF, F. Gelis, R. Venugopalan, work in progress

  2. Motivations • J/psi suppression(Matsui-Satz, 1986) • - anomaly was found at CERN • - on top of “Nuclear absorption” - understood as independent F absorption by nucleons NA50, Santos QM04

  3. Motivations • J/psi suppression(Matsui-Satz, 1986) • - anomaly was found at CERN • - on top of “Nuclear absorption” • Heavy quark productionat high energy - info on initial (nuclear) gluon distribution - particle production in nuclear medium

  4. 2R/g Scales in the problem • heavy quark creation - tp ~ 1/(2mc) ~ 0.1 fm • quarkonium binding - tc ~ 1/DE ~ 1/(asmc) ~ 0.3 fm • nucleus 2R~10 fm, inter-nucleon ~ 2 fm • in n-n CM frame, nucleus becomes thinner • - 2R/g ~1fm(SPS), 0.1fm(RHIC), 0.01fm(LHC) • - NB wee partons ignored • in A-rest frame, coherence length gets longer • - tcg ~3fm(SPS), 30fm(RHIC), 600fm(LHC) Coherence becomes more important at higher energies

  5. Attenuation of a pair bound state HF, T. Matsui, ’02 • Simple model of coherent scattering effect • Non-abeian analog of ‘superpenetration’ • Eikonal propagation of a bound quark-pair

  6. Attenuation of a pair bound state • Simple model of coherent scattering effect • Non-abeian analog of ‘superpenetration’ • Eikonal propagation of a bound quark-pair • Target; Random Gaussian gauge field

  7. Attenuation of a pair bound state • Simple model of coherent scattering effect • Non-abeian analog of ‘superpenetration’ • Eikonal propagation of a bound quark-pair • Target; Random Gaussian gauge field • Survival probability, roughly,

  8. Attenuation of a pair bound state • Survival probability, asymptotically • Simple model of coherent scattering effect • Non-abeian analog of ‘superpenetration’

  9. Attenuation of a pair bound state • Coherent scattering results in • non-exp, power-law suppression • Simple model of coherent scattering effect • Non-abeian analog of ‘superpenetration’ Exp(-L/Lin)

  10. 2R/g Production: pair mom modified • 1/2mc<<2R/g<1/DE case - produced pair is scattered within the target before resonance formation - rescattering changes pair momentum Qiu-Vary-Zhang, PRL ’02

  11. Production: pair mom modified • 1/2mc<<2R/g<1/DE case - produced pair is scattered within the target before resonance formation - rescattering changes pair momentum Qiu-Vary-Zhang, PRL ’02 Formation probability w/ threshold (cf. color evaporation model) sums leading A-enhanced terms NB. For a certain L, e2L>Mth2

  12. Production: pair mom modified • 1/2mc<<2R/g<1/DE case - produced pair is scattered within the target before resonance formation - rescattering changes pair momentum Qiu-Vary-Zhang, PRL ’02 Formation probability w/ threshold (cf. color evaporation model) sums leading A-enhanced terms smears mom dist HF, ’03 • different behavior at large L higher order terms need to be studied

  13. Production: pair mom modified • 1/2mc<<2R/g<1/DE case - applied to AA collision by adjusting ‘L’ PbPb

  14. 2R/g Production: the MV model • 2R/g <~ 1/2mccase - all nucleons along the path acts on simultaneously in heavy quark production

  15. Production: the MV model • 2R/g <~ 1/2mccase - all nucleons along the path acts on simultaneously in heavy quark production -in the MV model, ‘wee’ partons (~ classical fields) of nucleus interact and create hadrons - quark production in classical field - known analytically to O(rprAinfty) in Lorentz gauge Blaizot-Gelis-Venugopalan, ’04

  16. Production: the MV model • 2R/g <~ 1/2mccase - all nucleons along the path acts on simultaneously in heavy quark production -in the MV model, ‘wee’ partons (~ classical fields) of nucleus interact and create hadrons - quark production in classical field - known analytically to O(rprAinfty) in Lorentz gauge Blaizot-Gelis-Venugopalan, ’04 Schematically

  17. Production: the MV model Blaizot-Gelis-Venugopalan, ’04 • Quark pair production cross section • kT kick on the quarks during production breaks kT factorization

  18. Production: the MV model • large Nc limit for nucleus (collinear form for proton) - 4-, 3-point funcs reduce to a product of 2-point function, C - C expresses Glauber’s multiple scattering of each quark • Implications to quarkonium • - kT kicks on quarks smear out the relative pair mom distribution • - naturally change the formation of the bound state

  19. Production: the MV model 3-point function, fqqg

  20. Outlook • High energy quarkonium, scattering coherently with nuclear target, attenuates by power-law falling • In pA colls at RHIC energy or higher, coherent interaction becomes important even for charm quark production, which also will modify quarkonium production rate. • The MV model will provide a natural framework to study this problem. • study both of quarkonium and heavy quarks will be interesting and on-going.

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