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Intrinsic and extrinsic p t effects on J/ y shadowing This work , on behalf of

Transverse momentum dependence of J/ Y shadowing effects in  s NN = 200 GeV d+Au collisions at RHIC (and its consequences in Au+Au). Intrinsic and extrinsic p t effects on J/ y shadowing This work , on behalf of

josephine-strong
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Intrinsic and extrinsic p t effects on J/ y shadowing This work , on behalf of

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  1. Transverse momentumdependence of J/Y shadowing effects in sNN=200 GeV d+Au collisions at RHIC (and itsconsequences in Au+Au) Intrinsic and extrinsic pteffects on J/y shadowing This work, on behalf of E. G. Ferreiro F. Fleuret J.-P. Lansberg A. Rakotozafindrabe Work in progress… F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  2. Introduction • Shadowing and d+Au PHENIX data • 2 remarks: • Need at least 2 different sbreakup to fit RdAu.vs.Ncoll • No prediction for RdAu.vs.pT 200 GeV/c PHENIX d+Au data Phys. Rev. C 77, 024912 (2008) Shadowing modelisation from R.Vogt, Phys.Rev. C71 (2005) 054902 Assuming pT=0 RdAu -2.2<y<-1.2 -0.35<y<0.35 1.2<y<2.2 Ncoll • Goal of thiswork: introduce J/YpT in shadowing computation • In this talk, we’llconsider EKS98 shadowing only • Investigatingtwomechanisms • g+g  J/Y  « intrinsic » scheme: the pT of the J/Ycomesfrom initial partons • Can beparametrizedusing the data • g+g  J/Y+g  « extrinsic » scheme: the pT of the J/Yisbalanced by the outgoing gluon • Need a model to bedescribed Nuclear modification factor F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  3. This workGlauber modelisation of CNM effects • An event generator to produce J/Ysamples • Based on a glauber Monte Carlo • Use J/Y production models (or data) to get (J/Y) y, pT, x1, x2, Q² • Using EKS98, modify the J/Y cross section according to: • Compare with data using: • Use « intrinsic » (g+gJ/Y) and « extrinsic » (g+g  J/Y+g) schemes as inputs to get J/Ykinematics information See arXiv:0801.4949 for more details F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  4. « intrinsic » J/Y productiong+g  J/Y y, pT, x1, x2, Q² can be determined with data : using PHENIX p+p data Phys. Rev. Lett. 98, 232002 (2007) kinematics: • y, pT randomly picked on the data • Then, compute kinematics as input of shadowing factors F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  5. « extrinsinc » J/Y production g+g  J/Y+g Color singlet and color octet calculationscomparedwith PHENIX run 3 (200 GeV/c) p+p data : PHENIX, Phys. Rev. Lett 92, 051802 (2004). S-channelcutmechanism(extension of the color singlet model) comparedwith PHENIX run 5 (200 GeV/c) p+p data: Haberzettl and Lansberg, Phys. Rev. Lett. 100, 032006 (2008). Good description for pT > 2 GeV/c No description below 2 GeV/c  Use s-channelcut model in the following Model provides y, pT, x1; get and Q²=M²+pT² F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  6. d+Au Rapiditydependenceintrinsic.vs.extrinsic Intrinsic (g+g  J/Y) Small differencewhenaddingpT. In p+p: <pT> < 2 GeV/c No significantdifferencebetweenpTfrom central and forwardrapidity Extrinsic (g+g  J/Y + g) significantdifferencebetweenintrinsic and extrinsicscheme : more antishadowingatmidrapidity ; less shadowing atforwardrapidity. No breakup cross section used for this plot F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  7. d+Au Rapiditydependencebreakup (absorption) cross section Nuclear absorption added Intrinsicscheme: • following PHENIX PRC 77, 024912 (2008), best match isobtainedwithsbreakup = sabs = 2.8 mb Extrinsicscheme: • sbreakup = 2.8 mb is not enough for extrinsicscheme to match data • Trysbreakup = 4.2 mb as measured by NA50.  good match • to bedone: determining best sbreakupusingc² minimization F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  8. d+Au Centralitydependenceintrinsic .vs. extrinsic (w/ absorption) RdAu .vs. Ncoll Backwardrapidity :  Intrinsic + sbreakup=2.8 mb fails to reproduce the data (betterwithsbreakup=5.2mb) Extrinsic + sbreakup = 4.2 mb reproduces the data Midrapidity:  Both scenarios have the samebehavior. Good match Forwardrapidity:  Both scenarios have the samebehavior. Good match PHENIX Phys. Rev. C 77, 024912 (2008) Ncoll « extrinsic » shows a fair agreement with the data using the same sbreakup = 4.2 mb for all rapidities F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  9. d+Au Transverse momentumdependenceintrinsic .vs. extrinsic (w/ absorption) RdAu .vs. pT Backwardrapidity:Samebehavior for both scenarios ; difficult to conclude about the slope  ____________________________ Midrapidity:Samebehavior for both scenarios and match the data  ____________________________ Forwardrapidity:Both scenarios have the samebehavior ; slopesseemsmallerthan in the data  pTbroadening ? Cronin effect ? Difficult to conclude Need more precise data F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  10. Au+Au centralitydependenceintrinsic .vs. extrinsic (w/ absorption) • Intrinsic • Same CNM suppression at forward and central rapidity. More « additionnal » suppression observed at forward than at mid rapidity • Extrinsic • More CNM suppression atforwardthanat central rapidity. Seems to be consistent with the behaviorobserved in most central data. RAA/CNM to bedone… Npart Npart F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  11. Au+Au rapiditydependenceintrinsic .vs. extrinsic (w/ absorption) Intrinsic • Shape of CNM effects ~flat for all centralitybins suppression due to HDM effectsislargeratforwardrapiditythanat central rapidity. Extrinsic • Shape of CNM effectsischangingwithcentralityand follows the data  suppression due to HDM effectsis ~flat for all centralitybins. F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  12. Au+Au transverse momentum dependence Intrinsic Extrinsic • No major difference between intrinsic and extrinsic • Both models seem to reproduce fairly well the slopes of |y|<0.35 data at any centrality • Both models fail to reproduce the slopes of |y|  [1.2,2.2] data for central events  larger slope in the data (Cronin effect ?) • Will look at <pT²>… F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  13. Conclusion • We have investigatedeffects of « intrinsic » (g+g  J/Y) and « extrinsic » (g+g  J/Y+g) pTschemes on shadowing (using EKS98) • Observe significantdifferences in the shadowing effectswhenusing the twoschemes itis important to understand J/Y production in p+p collisions • Thesedifferences affect the conclusion wecanmakewhenstudying HDM effects in Au+Au collisions • The differencebetweenRAuAuforward / RAuAucentralcanbepartly due to CNM effects • The RAuAu.vs.yshapecanbepartly due to CNM effects • Transverse momentumstudiesgiveadditionnal information • RAuAu.vs.pTshapeisfairlywellreproduced by CNM effectsatmid-rapidity • RAuAu.vs.pTslopeissmaller for CNM effectsthan for the data atforwardrapidity • More precise d+Au data are needed to betterconstraint the models new d+Au data have been recordedthisyear (run 8)  30 times more data… F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  14. Backup slidex1,2.vs.y intrinsic extrinsic x1 x2 x1 x2 y y F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

  15. d Au X2 X2 X1 X1 X1 X2 J/ North y > 0 J/ South y < 0 J/ Central y = 0 rapidity y Backup slideEKS98 Central South North Eskola, Kolhinen, VogtNucl. Phys. A696 (2001) x2 PHENIX μ, North PHENIX m, SOUTH PHENIX e Small x2 (in Au) ~0.003 Large x2 (in Au) ~0.090 Intermediate x2 ~ 0.02 F. Fleuret LLR-CNRS/IN2P3 FFLR - Hard Probes 2008

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