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Elena G. Ferreiro Universidade de Santiago de Compostela, Spain

Heavy Ion Collisions in the LHC Era 16 - 20 July 2012, Quy Nhon , Vietnam. J/ψ and ϒ production in proton+nucleus collisions : lessons from RHIC for the 2012 p+Pb LHC run. Elena G. Ferreiro Universidade de Santiago de Compostela, Spain.

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Elena G. Ferreiro Universidade de Santiago de Compostela, Spain

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  1. Heavy Ion Collisions in the LHC Era 16 - 20 July 2012, QuyNhon, Vietnam J/ψ and ϒ production in proton+nucleuscollisions: lessonsfrom RHIC forthe 2012 p+Pb LHC run Elena G. Ferreiro Universidade de Santiago de Compostela, Spain in collaboration with F. Fleuret, J-P. Lansberg , N. Matagneand A. Rakotozafindrabe EPJC61 (2009), PLB680 (2009), PRC81 (2010), NPA855 (2011),FBS53 (2012), arXiV:1110:5047

  2. Motivation • A lot of work trying to understand A+A data (since J/y  QGP signal) Quarkonium as a hint of deconfinement • If we focalise on p+A data (where no QGP is possible) only cold nuclear matter (CNM) effects are in play: shadowingand nuclear absorption EMC andenergyloss LHC p+Pbrun Quarkonium as a hint of coherence • In fact, the question is even more fundamental: p+pdata we do not know the specific production kinematics at a partoniclevel: (2→2,3,4) vs (2→1) Quarkonium as a hint of QCD 1 E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 1

  3. Contents • Ourgoal: • ToinvestigatetheCNM effects and the impact of the • specific partonic production kinematics • 3 ingredients: • Quarkoniumpartonic production mechanism • Shadowing • Nuclear absorption • • ResultsonJ/y production @ RHIC and LHC • Toextend our study to ϒand other CNM effects : • fractionalenergyloss • gluon EMC effect • • Resultsonϒand J/y production @ RHIC • • Resultsonϒ @ LHC 2 E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 2

  4. Background E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 3

  5. Nuclear absorption: a final cold nuclear mattereffect Particlespectrumalteredbyinteractionswiththe nuclear mattertheytraverse => J/Ysuppressiondueto final stateinteractionswithspectatornucleons • Usual parameterisation: (Glaubermodel) Sabs = exp(-r sabs L ) nuclear matter density break-up cross section path length Energydependence • At lowenergy: the heavy systemundergoessuccessiveinteractionswithnucleons in itspath and has tosurviveall of them=> Strong nuclear absorption • At highenergy: thecoherencelengthislarge and theprojectileinteractswiththe nucleus as a whole=> Smaller nuclear absorption In terms of formation time: C. Lourenço et al. sabs@ mid y < sabs@ forward y? Rapiditydependenceof nuclear absorption? 5 E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 4

  6. Shadowing: aninitialcold nuclear mattereffect • Nuclear shadowing is an initial-state effect on the partons distributions • Gluon distribution functions are modified by the nuclear environment • PDFs in nucleidifferentfromthesuperposition of PDFs of theirnucleons Shadowingeffectsincreaseswithenergy (1/x) and decreasewith Q2 (mT) antishadowing Theshadowingcorrections dependonthepartonicprocessproducingthe J/Y sinceitaffectskinematics (x,Q2) shadowing EMC 3 E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 5

  7. On the kinematics of J/y production: two approaches • CNM -shadowing- effects depends on J/y kinematics (x,Q2) • J/y kinematics depends on the production mechanism => Investigatingtwoproductionmechanisms(includingpTforthe J/y): • g+g → J/y • • intrinsic scheme: the pTof the J/y comes from initial partons • Not relevant for, say, pT>3 GeV • Only applies if COM(LO, as2) is the relevant production mechanism at low pT 2→1 2→2, 3, 4 • g+g → J/y+g, gg,ggg,… • •extrinsicscheme: thepTof the J/yisbalancedbytheoutgoingparton(s) • COM (NLO, NNLO), • CSM (LO, NLO, NNLO) for a given y, larger x in extrinsic scheme => modification of shadowing effects E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 6

  8. Howpartonickinematicsaffects CNM: J/y in d+Au @ RHIC 2→1 g+g → J/y 2→2 g+g → J/y+g E. G. Ferreiro, F. Fleuret, J. P. Lansberg and A. RakotozafindrabePRC 81 (2010) 064911 • shadowingdependsonthepartonicprocess: 2→1 or2→2 • in orderto reproduce data @ RHIC: nuclear absorption sabsextrinsic > sabsintrinsicthe kinematics matter for the extraction of sabs 6 E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 7

  9. J/y in Au+Au @ RHIC: rapidity dependence • The J/y suppression from shadowing is y-dependent Reminder: sabstaken as constant • Can account for a part of the y-dependence of the most central data E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 8

  10. J/y in Pb+Pb @ LHC: centralitydependence vs data “CEM NLO” before kT smearing “Traditional” 2 → 2 E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 9

  11. J/y in Pb+Pb @ LHC: centralitydependence vs data “CEM NLO” beforekTsmearing “Traditional” 2 → 2 • Uncertainty bands: • mFfrom 0.5 mT to 2 mT • (as done in pp for g(x,mF) withktsmearing withoutktsmearing ktsmearingprocedure isappliedafter the (x1,x2) integration underlying partonic model E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 10

  12. Something new… searchingforother CNM effects: ϒproduction • Gluon EMC effect • Fractionalenergyloss E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 11

  13. Absorption: ϒvs J/y uncertaintyprinciple: time needed – in their rest frame to distinguish the energy levels of the 1S and 2S states RHIC: sϒabs< 1 mb E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 12

  14. nPDFuncertaintyonϒproduction in d+Au @ RHIC Extrinsic scheme: sabs=0 mb, sabs= 0.5mb , sabs= 1 mb in 3 shadowing models • backward: ok within uncertainties • central: reasonable job • forward : clearly too high (for any σabs) Physicalinterpretation • backward: EMC effect • central: antishadowing • forward : shadowing≈1 energy loss is needed 16 E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 13

  15. Searchingfor new effects: gluonEMConϒ in dAu @ RHIC E. G. F., F. Fleuret, J. P. Lansberg and A. Rakotozafindrabe arXiV:1110:5047 EMC antishadowing Let us try to increase the suppression of g(x) in the EMC region, thr shadow incert.: wehaveusedthreeof the EPS09 LO sets: one with a quark-like EMC gluon suppression, and the two limiting curves Works better for backward region What about the forward region? E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 14

  16. Searchingfor new effects: energylossonϒin dAu @ RHIC WORK IN PROGRESS, preliminary E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 15

  17. Searchingfor new effects: energylossonϒin dAu @ RHIC WORK IN PROGRESS, preliminary E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 16

  18. Work in progress: ϒproduction @ LHC • Shadowing effect is not small Remember that in PbPb collisions at y = 0 shadowing effect is squared compared to pPb E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 17

  19. Work in progress: ϒproduction @ LHC • Shadowing effect is not small Remember that in PbPb collisions at y = 0 shadowing effect is squared compared to pPb • Energy loss also likely matters, in particular in the most forward rapidity E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 18

  20. Work in progress: ϒproduction @ LHC • Shadowing effect is not small Remember that in PbPb collisions at y = 0 shadowing effect is squared compared to pPb • Energy loss also likely matters • Overall, nuclear matter effects are not small they should be accounted when analysingPbPb data E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 19

  21. Conclusions • Wehavestudiedtheinfluence of specificpartonickinematics within2 schemes: intrinsic (2→ 1) and extrinsic (2→2) pT fordifferentshadowings includingnuclear absorptionand differentpartonicmodels • forJ/y d+Aucollisions @ RHIC A+A collisions @ RHIC and LHC CNM strongeffects at bothenergy • forϒin d+Aucollisions @ RHIC: EMC effectin thebackwardregion fractionalenergylossin thecentral & forward region • energylosscan alsoaffectJ/y @ RHIC •work in progress: ϒproduction @ LHC http://phenix-france.in2p3.fr/software/jin/index.html 22 E. G. Ferreiro USCϒand J/ψ production in pA: from RHIC to LHCHIC in the LHC Era 19 July 2012 20

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