Review of Electromagnetic Probes O. Drapier LLR-�cole

Review of Electromagnetic Probes ? O. Drapier LLR-École Polytechnique, France « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 1 Electromagnetic probes ? t kinetic freeze-out chemical freeze-out hadronization chiral symmetry ? thermal equilib. ? chemical equilib. ? deconfinement ? p,k l± B B g p,n hadrons mixed phase ? Direct Photons plasma partons thermalization Single leptons, Dileptons z « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 2 Photons ! (S.Bathe, 6b) Compare to NLO pQCD • L.E.Gordon and W. Vogelsang • Phys. Rev. D48, 3136 (1993) See next talk by C. Gale • excess above pQCD Compare to thermal model • D. d’Enterria, D. Perresounko • nucl-th/0503054 2+1 hydro T0ave=360 MeV(T0max=570 MeV) • data above thermal at high pT t0=0.15 fm/c Compare to thermal + pQCD • data consistent with thermal + pQCD « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 3 Low mass dileptons  From low energies … p+Cu, 12 GeV C+C, 2 AGeV within acceptance  To SPS … See next talk by C. Gale R.Muto, Kek-PS-E325,6a R.Holtzmann, Hades, 6a SPS, 158 AGeV S.Damjanovic, NA60, 6a D. Miskowiec, CERES « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 4 Outline  Charm and Charmonium « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 5 Not exactly a Review of Electromagnetic Probes O. Drapier LLR-École Polytechnique, France « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 6 Let’s start with NA50 J/y  Precise re-analysis of p-A data     s scaling, kinematical domain, neutron halo, … sabs(J/y) = 4.18 ± 0.35 mb sabs(y’) = 7.6 ± 1.1 mb  Why sabs ? Why not Aa ? L. Ramello, NA50 7 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 a vs sabs Aa = straight line here e –r sabs = straight line here σp A  σ 0 A α σp A  σ0 A exp σabs ρL σ p A  σ0 σ abs  1 T sσ   A abs  A  ds C. Lourenço Student’s session  Not equivalent !  Depends on which nuclei you take  + r < L > or < rL > are only approximations Calculations by Ruben Shahoyan « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 8  e – sabs = intuitive if J/y disappearance in an absorbing medium. May depend on s !! sabs  Combination of energy loss of the initial parton + J/y « absorption » in nuclear matter  Doesn’t seem to play a  Energy loss of initial gluon: role at NA50 Xf,  Depends on Xf otherwise would be  Less important at RHIC seen on the  M. Leitch, E866, Eur.Phys.J.A (2004) 19, S01, 129 Curve from Kopeliovich et al., Nucl. Phys. A696 (2001) 669  Can be even much more complex that that ! B ds() / dycm at ycm =0 P. Cortese, NA50, 5b P. Cortese, NA50, 5b « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 9 NA60  In+In @ 158 A.GeV  E. Scomparin, R. Arnaldi, 6a  Anomalous suppression !  Even if they fit NA50 data  Onset in the range 80 < Npart < 100  Not reproduced by models  Even if they fit NA50 data PLATEAU ??? Satz, Digal, Fortunato Rapp, Grandchamp, Brown Capella, Ferreiro R. Arnaldi, NA60 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 10 What is the relevant variable ?  There is NO unique universal variable  Depends on what you want to show  e.g. : anomalous suppression is NOT an absorption by nuclear matter  More tricky if you need to compare different s !!!  e.g. e allows comparisons L or L don’t R. Arnaldi, NA60 11  pure geometry « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 What is the relevant variable ?  So, in principle we should:  Calculate all the effects that might change with s  Subtract them or plot them on top of the data for comparison  Plot the result vs the variable corresponding to the effect you want to test/rule out  But these variables are model dependent  & experiment dependent = nobody else than the experiment can calulate these quantities L. Ramello, NA50 NA60 Number of Participants PHENIX 0-5 % « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 12 SPS -> RHIC  Charm and charmonium cross-sections J. Dunlop  Opens the door for cc recombination into J/y  N(cc) up to 40 in a central Au+Au collision !  R.L. Thews & R.L. Mangano, nucl-th/0505055 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 13 Open charm measurements @ SPS ?  The « intermediate mass dilepton » puzzle @ SPS:  Is there an enhancement of charm, or charm-like contribution ? Dimuon weighted offsets in NA60 R. Shahoyan, 5b  For now, not enough precision to measure charm crosssection … « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 14  The answer is : NO, the excess exists, but it’s PROMPT Open charm @ RHIC  Open charm is measured by  Single « non-photonic » electrons in PHENIX and STAR  Direct D->kp in STAR (see H. Zhang, 5c) S. Butsyk, 5a J. Dunlop  Limited PT domain  « binary scaling » = as Ncoll  MORE PRECISION NEEDED ! PHENIX, S.S. Adler, et al., PRL 94 082301 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 15 Charm @ RHIC : high PT suppression  Nuclear modification factor (S. Butsyk, 5a, J. Bielcik, 5c)  For more details, see J. Bielcik this afternoon See talk by X. Dong J. Dunlop Djordjevic et al, nucl-th/0507019  High PT suppression does not change charm yields « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 16 Charm @ RHIC : Flow !  Charmed particles have a large V2 at RHIC !  Charm « quenching » and V2 were not expected  Hard process -> no flow  Influence of light quark flow ?  Higher quark mass -> less gluon radiation (’’dead cone effect’’)  e.g. : Y. L. Dokshitzer & D.E. Kharzeev, Phys.Lett.B519(2001)199-206 See talk by X. Dong STAR, F. Laue, 5a S. Butsyk, 5a Theory: Greco, Ko, Rapp: PLB 595 (2004) 202 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 17 Cold nuclear effects  Heavy flavor = probe for « cold » nuclear effects  Parton distribution functions are modified in nuclei  e.g. in d-Au collisions : Pb / p d Shadowing Anti Shadowing Au X rapidity y X1 X2 X1 X2 X1 X2 J/y North y>0 18 J/y South y<0 J/y Central y < 0 Anti-shadowing Nothing ? Shadowing « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 Cold nuclear effects  PHENIX d+Au @ 200 GeV (nucl-ex/050732, W. Xie, 5c)  (anti)shadowing clearly visible  sabs seems lower than @ SPS  ~1 mb, 3mb overestimated  Dependence with centrality  For Au+Au = mirror distribution X 19 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 Now let’s move to PHENIX J/y  J/y in STAR ! See H. Zhang, 5c this afternoon  J/y in PHENIX : H. Büsching, H. Perreira Da Costa, 6b J/y  muon arm 1.2 < |y| < 2.2 J/y ee Central arm -0.35 < y < 0.35 AuAu CuCu AuAu CuCu dAu ee ee    200 GeV/c 200 GeV/c 200 GeV/c 200 GeV/c 200 GeV/c CuCu  62 GeV/c 20 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 J/y in PHENIX  Tempting to plot NA50 points on top of this, isn’t it ?  Well … interesting but …  Meaning of Npart when s * 10 ?  NA50 points normalized to p+p  What if sabs different ?  Shadowing ? H.Pereira Da Costa, 6b  Better : compare to absorption + shadowing  Suppression = 35 to 40 % wrt to sabs = 3mb (overestimated)  ~ equivalent to NA50  Need better reference !!! « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 21 J/y in PHENIX  Models:  The models « which fit NA50 data » overestimate the suppression  Regeneration needed ???  MAYBE, but  These models DO NOT fit NA60 !  Comovers severely underestimate suppression in In+In  Rapp & Grandchamp doesn’t saturate as seen in the data  Only Satz fits the end of the plateau with Xc suppression only.  NO direct J/y suppression ? See talk by M. Nardi R. Arnaldi, NA60 c J/y ?  Would be consistent with recent lattice QCD calculations Satz Rapp-Grandchamp Capella-Ferreiro « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 22 - recombinations ? c-c  It seems that these models can reproduce the data, when they turn on the recombination process  Consequences on the other variables ? « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 23 Rapidity distributions  Rapidity distribution of recombined J/y is supposed to be peaked at y=0 (e.g. R.L. Thews & al., nucl-th/0505055)  True IF charm distribution ~ J/y in p+p ! p+p data mainly « off-diagonal » « diagonal » pQCD, adjust  But Au+Au charm rapidity distributions might be very flat ! H.Pereira Da Costa, 6b « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 24 Rapidity distributions  Comparing charm cross-sections in PHENIX central and muons arms:  Au+Au charm rapidity distributions might be very flat in Au+Au !  Just an indication, because of the limited PT domain See talk by Y. Kwon, 5c this afternoon ! PHENIX PRELIMINARY  If flat distribution of charm production :  Lowers charm density -> less regeneration  Rapidity distribution of regenerated less peaked at 0 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 25 PT distributions ?  PT distribution of recombined J/y is very narrow (R.L. Thews & al., nucl-th/0505055) mainly « off-diagonal » « diagonal » Without With  Leads to a drastic reduction H.Pereira Da Costa, 6b of in case of recombination  BUT calculated from p+p and d+Au (via )  Large error bars  Need for more p (or d) + A data !! (e.g. p+p to d+Au in e±) « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 26 PT distributions ? Back to SPS  NA50 suppression at low PT …  Compatible with high PT charm pairs escaping the hot region before forming the J/y  The same mechanism at RHIC would lead to an increase of  Very different from regeneration Low PT pairs cannot form a J/y High PT pairs can escape At RHIC, much higher than at sps, but plasma longer lived. What is the net result for J/y ? 27 F. Karsch & R. Petronzio M.C. Chu & T. Matsui J.P. Blaizot & J.Y. Ollitrault « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 Is there a J/y flow ?  Charm flows  recombined J/y must flow !  Directly produced J/y shouldn’t flow but suppression might be stronger out of reaction plane (as for Jets) …  Can simulate some flow for surviving J/y ? Regenerated J/y should lie on this curve V2/2 vs PT/2 ! solid: STAR open: PHENIX PRL91(03)  Comovers should be more active in-plane   those J/y which survive interactions with comovers would have a negative V2 ???? 28 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 Conclusion (1)  A LOT OF BEAUTIFUL NEW DATA !  SPS :  CERES excess confirmed by NA60  Intermediate mass excess in dimuon spectra confirmed by NA60  IT IS NOT OPEN CHARM, it’s prompt  NA50 has re-analyzed p+A reference  Anomalous J/y suppression confirmed by NA60 in In+In  RHIC      Direct photons at low PT from PHENIX, consistent with thermal emission Open charm is suppressed at high PT Significant flow observed for open charm J/y suppression is seen by PHENIX, not stronger than in NA50 Models without recombination of charm quarks are unable to account for the data « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 29 Conclusion (2)  WE MUST TAKE SOME TIME, Interpreting J/y suppression is a tricky thing  Reproduce ALL SPS data  Extrapolate to RHIC  Shadowing  Normal absorption  Measured flow  Measured Y and PT distributions  THEN ONLY compare to RHIC data  We need GOOD REFERENCES !  p+A @ SPS (NA50, NA60 to be analyzed)  p+A or d+A at RHIC  We need good statistics + several systems !!!! « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 30 Conclusion (3) NA38, QM’91 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 31 Thank You ! Special thanks to: F. Fleuret for his help for preparing this talk, L. Kluberg, C. Lourenço, D. D’Enterria, R. Granier de Cassagnac and many others, for usefull discussions « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 32 Backup Slides « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 33 Kharzeev, Nardi & Satz D.Kharzeev, M.Nardi and H.Satz, Phys. Lett. B405 (1997) 14 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 34 Heavy flavor production  ’’Onia’’ production  Leading order at low x = ’’gluon fusion’’  Sensitive to: Initial state Parton distribution functions pT broadening Parton energy loss in the initial state ? Polarization ? J/y or  Final state Parton energy loss in the hot & dense medium ? Thermal enhancement ? Flow ? + feed-down (e.g. B or c-> J/y) 35 « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 Heavy flavor production  Open charm (or beauty) production  Leading order at low x = ’’gluon fusion’’  Sensitive to: Initial state Parton distribution functions pT broadening Parton energy loss in the initial state ? Polarization ? Final state Parton energy loss in the hot & dense medium ? Thermal enhancement ? Flow ? « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 36 d-Au (√s = 200 GeV)  d-Au: binary scaling also holds for different centralities PHENIX PRELIMINARY PHENIX PRELIMINARY « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 37 Au-Au (√s = 62.4 GeV)  Open charm in Au-Au @ 62.4 GeV, as compared to ISR p-p data at the same incident energy  Also compatible with scaling PHENIX PRELIMINARY « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 38 Recent evolutions in f µµ B.R. 1999: only average of values of f photoproduction 2000 BRµµ included in the overall PDG fit new imprecise measurement of ee->µµ : increase of BRµµ 2002 better ee->µµ measurement, confirming universality principle 1999-2000-2002 : 2.5 – 3.7 – 2.87 2004: BR µµ = (2.85±0.19) 10-4 ; BR ee = (2.98±0.04) 10-4 Year PDG average 1998 2.5 PDG fit 3.7 2.87 ee->µµ CS is not used in the fit Achasov 99C (3.30) appears Achasov 01G (2.87) appears 39 f f 2000 2.5 2002 2.5 2004Review of electromagnetic2.85 », OD @ Quark Matter ’05, Budapest, this08, 2005 2.5 No new data on Aug. mode « probes Phi puzzle « Review of electromagnetic probes », OD @ Quark Matter ’05, Budapest, Aug. 08, 2005 40