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Results on deuteron – gold collision at forward rapidity in PHENIX IhnJea Choi (UIUC) For the PHENIX collaboration 01/04/2012 1/4/12 1.

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Presentation on theme: "Results on deuteron – gold collision at forward rapidity in PHENIX IhnJea Choi (UIUC) For the PHENIX collaboration 01/04/2012 1/4/12 1."— Presentation transcript:

1 Results on deuteron – gold collision at forward rapidity in PHENIX IhnJea Choi (UIUC) For the PHENIX collaboration 01/04/2012 1/4/12 1

2 Outline d+Au collision – Nuclear Modification Factor – Competing models – CGC, Shadowing, Energy Loss, Absorption Experiment – RHIC – RHIC luminosity, PHENIX experiment – MPC ( Muon Piston Calorimeter in PHENIX ) Hadron R dA, R CP results at different rapidity ranges – Hadron and decay muon – Single electron and single muon – J/ψ, Υ – Light vector meson ( ϕ, ρ, ω) Di-hadron azimuthal angle correlation results – CY, I dA, J dA – Mid-forward rapidity correlation – Forward-forward rapidity correlation Summary 1/4/12 2

3 d+A Collision 1/4/12 3 Deutron Parton x _d Au Parton x_ Au Deutron Parton x _d Au Parton x _Au Forward rapidity (Deutron going direction) x_ d > x_ Au (Low x in Au) Backward rapidity (Au going direction) x_ Au > x_ d RHIC experiments have made an amazing array of measurements in d+Au to understand cold nuclear matter Initial state effects vital to interpreting results from heavy ion collisions Are effects at forward rapidity due to gluon saturation effects (have we reached a regime of QCD where non-linear effects are important)?

4 Why hadron production suppressed at forward rapidity ! 0 meson PHENIX | | < 0.35 R dA R dA ~ 1 at mid rapidity PRL 98 (2007), STAR, BRAHMS Forward STAR, BRAHMS Forward PRL 97 (2006), Nuclear Modification factor Cold Nuclear Matter(CNM) effect 1/4/12 4 Compelling theory models to explain this suppression at forward rapidity. Gluon saturation(or CGC) Nuclear shadowing/ E_loss Parton recombination Multi Parton Interaction (MPI) Momentum imbalance (recent paper) etc. STAR BRAHMS results show RdA < 1

5 As y, energy grows Color Glass Condensate & Effect Kharzeev, Kovchegov, and Tuchin, hep-ph/ Phase diagram of QCD evolution R pA suppressed at all values of p T as rapidity / energy grows. 1/4/12 Gluon density saturates for large denisites at small x Mechanism for gluon saturation Y is related to rapidity of produced hadron

6 Nuclear Shadowing / Energy Loss / Absorption 6 Energy loss of incident gluon shifts effective x F and produces nuclear suppression which increases with x F R(A/p) R=1 xFxF p A Absorption (or dissociation) of into two D mesons by nucleus or co-movers 1/4/12 Shadowing can arise from coherence - Small-x wavefunction spans large longitudinal distances λ ~ 1/p parton ~ 1/x i.e. the probe interacts with multiple target nucleons coherently

7 STAR RHIC Completed as of /4/12

8 Run3 d+Au 2.74 nb -1 MB triggered Run8 d+Au 85 nb -1 MB triggered 1/4/12 8 RHIC Luminosity

9 PHENIX Detector Muon Arms 1.2 < | η | < 2.4 Heavy Flavor muons J/Psi Charged hadrons Central Arms | η | < 0.35 Charged hadrons Neutral pions / η-mesons Heavy Flavor electrons Direct Photon J/Psi Muon Piston Calorimeter (MPC) 3.1 < | η | < 3.8 Neutral pions / η-mesons 1/4/12 9 Installed

10 PHENIX Muon Piston Calorimeter (MPC) Technology ALICE(PHOS) PbWO 4 avalanche photo diode readout 2.20 x 2.2 x 18 cm 3 crystals Acceptance: 3.1 < η < 3.9, 0 < φ < 2π -3.7 < η < -3.1, 0 < φ < 2π Both detectors built, installed Usable for 2008 d+Au run. MPC 0 Merged 0 1/4/12 10

11 1/4/12 Single hadron results 11

12 1/4/12 Phys. Rev. Lett. 94, (2005) Forward rapidity suppression No backward rapidity suppression (slightly enhanced) Consistent result with BRAHMS results ( η = 2.2 ) Punch Through Hadron & Hadron Decay Muon R CP 12 Mostly π +-,Κ +- and their decay into μ +- 12

13 1/4/12 Heavy quarks R dAu y = 1.6 Single muons from open charm & beauty: at forward rapidity suppressed at backward rapidity enhanced y = -1.6 Forward/Backward rapidity Single muon 13

14 CNM effects in J/ψ production Reasonable agreement with EPS09 nPDF + br =4 mb for central collisions but not peripheral EPS09 with linear thickness dependence fails to describe centrality dependence of forward rapidity region. PHENIX arXiv: v1 1/4/12 Gluon saturation model is good agreement with data at forward rapidity. 14

15 1/4/12 Y(1S + 2S + 3S) R dA R dAu = 0.84±0.34(stat.)±0.20(sys.), backward rapidity R dAu = 0.53±0.20(stat.)±0.16(sys.), forward rapidity Shows suppression at forward rapidity STAR Preliminary PHENIX Preliminary 15 Y access different low x range to J/Ψ : Y(x~0.01), J/ψ (x ~ 0.003)

16 Light vector meson R CP Comparing Nuclear Modification Factor R CP for ϕ, ρ, ω. forward rapidityBackward rapidity 1/4/12 16 Significant suppression in forward rapidity Stronger suppression for than and J/ ( Due to lighter quark content, and/or different production mechanisms? )

17 Forward π 0 results for R dA Suppression increase with increasing rapidity and centrality 1/4/12 17 PHENIX MPC

18 Forward π 0 R dA, Model Comparison 1/4/12 18 PHENIX MPC Shadowing Model overperdicted R dA of central collision data STAR forward R dA vs. Cronin + Shadowing + E_loss Model good agreement with data R. B. Neufeld, I. Vitev, and B-W Zhang arXiv: arXiv:

19 Di-hadron correlation 1/4/12 19

20 Accessing Low-x with Di-Hadrons Guzey, Strikman, Vogelsang, PL B603, 173 Di-Hadrons from Di-Jets Narrow x-range Smaller mean x, Constrain x-range ! Single Hadrons 1/4/12 20 However, x covered by single inclusive measurement is over wide range Includes shadowing, anti- shadowing, (EMC effect)

21 Measure of all particle pairs trigger particle (usually leading p T ) associate particle (lower p T ) trigger associate Beam view or transverse plane p+p, d+Au di-hadron correlations are similar at mid rapidity =0 is similar for d+Au (closed) and p+p (open) S.S Adler et al, Phys. Rev. C 73:054903,2006. Away-side Near-side Nearside peak Awayside Peak Beam View Di-hadron azimuthal angle correlation 1/4/12 21

22 CORRELATED N pair CY ( Conditional Yield ) Number of particle pairs per trigger particle after corrections for efficiencies, combinatoric background, and subtracting off pedestal. Di-Hadron pair Nuclear Modification factor CY / I dA / J dA Trigger comparison of d+Au jet associated counts relative to pp Single hadron Nuclear Modification Factor 1/4/12 22

23 J. L. Albacete and C. Marquet, PRL105 (2010) Di-hadron, CGC signature D. Kharzeev, E. Levin, and L. McLerran Nucl. Phys. A748 (2005) 627–640 Mid-forward di-hadron correlation Strength of correlation -> CGC phase or still in pQCD Expected large suppression in dAu than pp Expected angle broadening of away side peak Later, not reached low enough low x to see CGC effect J.L Albacete and C.Marquet, PRL105 (2010) Fwd-Fwd di-hadron correlation Access lower x region than mid-forward cor. CGC predicts significant b-dependence to suppression expected Width broadening expected at away side peak High pt of jet balanced by many gluons, Monojet Fwd di-hadron correlation measurements provide a good testing of CGC theory model 1/4/12 23

24 1/4/12 No significant broadening mid-forward rapidity azimuthal correlations (FMS-BEMC/FMS-TPC) Significant broadening for forward di-pion correlations (FMS-FMS) Strong suppression of away side peak for central forward-forward correlation with CGC prediction Di-hadron azimuthal correlation STAR 24 arXiv: v1 Multiple soft scatterings de-correlate the away side peak

25 dynamical shadowing, Energy Loss, Cronin Dihadron, Shadowing Di-Hadron Correlations allow one to select out the di-jet from the underlying event Constrains x range (probe one region at a time) Probe predicted angular decorrelation of di-jets (width broadening) (Qiu, Vitev PLB632:507,2006) 25 1/4/12

26 26 Dihadron, Multi Parton Interaction(MPI) At large forward rapidity range, azimuthal-angular independent pedestal component > expected significant enhancement at central dAu collision STAR PRL 97, π 0 : | | = 4.0, h ± : | η | 0.5 GeV/c PRD 83, M. Strikman, W. Vogelsang

27 Forward (Muon) – Mid rapdity, I dA Phys.Rev.Lett.96:222301,2006 d Au 1.4< η <2.0 η < | 0.35| No significant suppression or widening seen within large uncertainties! 1/4/ < η < -1.4 Only away side peak seen due to rapidity gap

28 Mid-Forward Correlations d Au PHENIX central spectrometer magnet Backward direction (South) Forward direction (North) Muon Piston Calorimeter (MPC) Side View d Au 0 s 0 or h +/- x gluon ~ (0.008,0.04) 28 1/4/12

29 Di-hadron Correlation, Mid-Fwd Mid-rapidity triggered | mid | < 0.35, fwd = Normalized by pi0 triggers and subtracted uncorrelated background (b 0 ) Due to large rapidity separation, only away side peak is seen. PRL107, (2011) Central d+Au collision shows suppression of away side peak No away side peak width broadening apparent | mid | < 0.35, fwd = /4/12 29

30 Away side peak widths broadening ? Trigger 0 : | | < 0.35, 2.0 < p T < 3.0 GeV Trigger 0 : | | < 0.35, 3.0 < p T < 5.0 GeV dAu 0-20% pp dAu 40-88% Widths are consistent between p+p and d+Au (all centralities) within large statistical and systematic errors No broadening seen (within errors) 1/4/12 30

31 Forward-Forward Correlations h 1,2 = 3.4 d Au PHENIX central spectrometer magnet Backward direction (South) Forward direction (North) Muon Piston Calorimeter (MPC) Side View d Au Mostly Merged 0 s clusters 0 x gluon ~ (0.001, 0.005) 1/4/12 31

32 Di-hadron Correlation, Fwd-Fwd Forward rapidity triggered Central d+Au appears to show significant suppression Angular broadening possible in central d+Au clus, 0 = PRL107, (2011) Normalized by pi0 triggers and subtracted uncorrelated background (b 0, ZYAM) Minimum cluster separation cut decrease amount of near side peak 1/4/12 32

33 J dA (Mid-Fwd, Fwd-Fwd) Suppression of J dA increases with N coll increase P T mid decrease P T fwd decrease Suppression Larger in fwd-fwd than mid-fwd Centrality dependent suppression Suppression of J dA increases with N coll increase Note: points offset from true to show p T dependence PRL107, (2011) 1/4/12 33

34 J dA versus R G Au ? Low x, mostly gluons J dA High x, mostly quarks Weak effects expected ~ R G Au b=0-100% Q 2 = 4 GeV 2 x Au EPS09 NLO gluons Eskola, Paukkunen, Salgado, JHP04 (2009)065 R G Au 1/4/12 Forward-Forward Mid-Forward 34 arXiv: v1

35 1/4/12 Dihadron momentum imbalance and correlations in d+Au collisions Initial- and final-state multiple interactions can affect dijet(dihadron ) production in p+A(d+A) This model explains both suppression and broadening of away side peak well. PHENIX J dA with model STAR Δ ϕ correlation with model Recent model predict Zhong-Bo Kang, Ivan Vitev, Hongxi Xing et al, arXiv( ) 35 dAu

36 Summary 1/4/12 d+Au collision at forward rapidity range enables us to study low-x physics PHENIX R dA, R CP of single hadron results showed suppression and consistent with STAR and BRAHMS data Di-hadron azimuthal angle correlation measurement Large suppression of away side peak seen in forward-forward correlation in d+Au relative to p+p (Jda) More suppressed in most central collision Angular Broadening of away side peak Mid-forward rapidity, no increase seen within errors Fwd-Fwd, increase seen in STAR data, currently inconclusive in PHENIX data Measurements of J dA ~ R G AU Recent model calculation for both J dA and away side peak width 36

37 Backup slide 1/4/12 37

38 1/4/12 38 Nuclear Shadowing models N. Armesto Hep-ph/ v2

39 Centrality Selection Charged particle track distribution representing 92% (+/- 2% systematic) of the 7.2 barn total Au+Au cross section. We then select event classes based on geometry (number of participating nucleons) using the Zero Degree Calorimeter and Beam-Beam Counter. 1/4/12 39

40 40 PHENIX Muon Piston Calorimeter Small cylindrical holes in Muon Magnet Pistons, Radius 22.5 cm and Depth 43.1 cm SOUTH PbWO 4 North Fwd-Fwd, x~(0.001,0.005) Mid-Fwd, x~(0.008,0.040) Mid-Bwd, x~(0.050,0.100) d(forward)Au(backward) 1/4/12

41 41 MPC Performance North MPC Decay photon impact positions for low and high energy 0 s. The decay photons from high energy 0 s merge into a single cluster Sometimes use (EM) clusters, but always corrected to 0 energy Clusters 80% 0 (PYTHIA) Trigger Near Far Jet1 Jet2 1/4/12

42 R CP and R dAu show strong rapidity dependence Brahms data Strong suppression at large rapidity (small-x) More central, larger rapidity range 1/4/12 42

43 Quarkonia Suppression in A+A Collisions Recent Gluon Saturation (CGC) calculations (arXiv: v1) also leave room for QGP effects in A+A collisions However, they do not help explain the stronger suppression at forward rapidity in A+A y=-1.7 y=0 y=1.7 PHENIX y=1.7 PHENIX y=0 ALICE y~3.2 1/4/12 43

44 1/4/12 J/ψ in d+Au – learning about CNM thickness dependence Nuclear effects are dependent on the density weighted longitudinal thickness of Au The forward rapidity points suggest a quadratic geometry dependence. Circle : Sys err. 44

45 Yield Extraction Examples Fitting function: Two Gaussian One Relativistc BW ( ) +Background (Defined by estimated shape) – yields stable when fitting procedure changes – yields using background subtraction (large uncertainty) Smaller fitting range: GeV Larger parameter range Estimated background y>0, Centrality: Larger fitting range: GeV Smaller parameter range 45 1/4/12


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