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Results on deuteron – gold collision at forward rapidity in PHENIX

Results on deuteron – gold collision at forward rapidity in PHENIX. IhnJea Choi (UIUC) For the PHENIX collaboration 01/04/2012. Outline. d+Au collision Nuclear Modification Factor Competing models CGC, Shadowing, Energy Loss, Absorption Experiment RHIC

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Results on deuteron – gold collision at forward rapidity in PHENIX

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

  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 RdA , RCP 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, IdA, JdA • Mid-forward rapidity correlation • Forward-forward rapidity correlation • Summary

  3. d+A Collision • 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)? Forward rapidity (Deutron going direction) Backward rapidity (Au going direction) x_d> x_Au(Low x in Au) x_Au> x_d Deutron Parton x_d Au Parton x_Au Deutron Parton x_d Au Parton x_Au

  4. Why hadron production suppressed at forward rapidity ! Cold Nuclear Matter(CNM) effect Nuclear Modification factor PHENIX|h| < 0.35 STAR, BRAHMS Forward h PRL 97 (2006), 152302 p0 meson RdA PRL 98 (2007), 172302 STAR BRAHMS results show RdA < 1 RdA ~ 1 at mid rapidity • 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.

  5. Color Glass Condensate&Effect Y is related to rapidity of produced hadron Kharzeev, Kovchegov, and Tuchin, hep-ph/0307037 Gluon density saturates for large denisites at small x As y, energy grows Phase diagram of QCD evolution RpA suppressed at all values of pT as rapidity / energy grows. Mechanism for gluon saturation

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

  7. STAR RHIC Completed as of 2006 Completed as of 2006

  8. RHIC Luminosity Run3 d+Au 2.74 nb-1 MB triggered Run8 d+Au 85 nb-1 MB triggered

  9. PHENIX Detector • Central Arms | η | < 0.35 • Charged hadrons • Neutral pions / η-mesons • Heavy Flavor electrons • Direct Photon • J/Psi • Muon Arms 1.2 < | η | < 2.4 • Heavy Flavor muons • J/Psi • Charged hadrons • Muon Piston Calorimeter (MPC) • 3.1 < | η | < 3.8 • Neutral pions / η-mesons Installed 2005-7

  10. PHENIX Muon Piston Calorimeter (MPC) Merged p0gg p0gg Technology  ALICE(PHOS) PbWO4 avalanche photo diode readout 2.20 x 2.2 x 18 cm3 crystals Acceptance: 3.1 < η < 3.9, 0 < φ < 2π -3.7 < η < -3.1, 0 < φ < 2π Both detectors built, installed 2005-2007 Usable for 2008 d+Au run. MPC

  11. Single hadron results

  12. Punch Through Hadron & Hadron Decay Muon RCP Mostly π+-,Κ+- and their decay into μ+- Phys. Rev. Lett. 94, 082302 (2005) • Forward rapidity suppression • No backward rapidity suppression (slightly enhanced) • Consistent result with • BRAHMS results ( η = 2.2 ) 12

  13. Heavy quarks RdAu • Single muons from open charm & beauty: • at forward rapidity suppressed • at backward rapidity enhanced y = -1.6 y = 1.6 Forward/Backward rapidity Single muon 13

  14. CNM effects in J/ψ production PHENIX arXiv:1010.1246v1 Reasonable agreement with EPS09 nPDF + br=4 mbfor central collisions but not peripheral EPS09 with linear thickness dependence fails to describe centrality dependence of forward rapidity region. Gluon saturation model is good agreement with data at forward rapidity.

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

  16. Light vector meson RCP Comparing Nuclear Modification Factor RCP for ϕ, ρ, ω. Backward rapidity forward rapidity • Significant suppression in forward rapidity • Stronger suppression for r/w than f and J/Y • ( Due to lighter quark content, and/or different production mechanisms? )

  17. Forward π0results for RdA PHENIX MPC Suppression increase with increasing rapidity and centrality

  18. Forward π0 RdA, Model Comparison R. B. Neufeld, I. Vitev, and B-W Zhang arXiv:1010.3708 STAR forward RdA vs. Cronin + Shadowing + E_loss Model good agreement with data PHENIX MPC Shadowing Model overperdicted RdA of central collision data

  19. Di-hadron correlation

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

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

  22. CY / IdA / JdA CORRELATED Npair CY ( Conditional Yield ) • Number of particle pairs per trigger particle after corrections for efficiencies, combinatoric background, and subtracting off pedestal. Trigger comparison of d+Au jet associated counts relative to pp Di-HadronpairNuclearModificationfactor Df Single hadron Nuclear Modification Factor

  23. 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 regionthan 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 J. L. Albacete and C. Marquet, PRL105 (2010) 162301 Fwd di-hadron correlation measurements provide a good testing of CGC theory model

  24. Di-hadron azimuthal correlation STAR No significant broadening mid-forward rapidity azimuthal correlations (FMS-BEMC/FMS-TPC) Significant broadening for forward di-pion correlations (FMS-FMS) arXiv:1008.3989v1 Strong suppression of away side peak for central forward-forward correlation with CGC prediction Multiple soft scatterings de-correlate the away side peak

  25. Dihadron, Shadowing dynamical shadowing, Energy Loss, Cronin (Qiu, Vitev PLB632:507,2006) • 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)

  26. STAR Dihadron, Multi Parton Interaction(MPI) PRD 83, 034029 M. Strikman, W. Vogelsang PRL 97, 152302 π0:|<η>| = 4.0, h±: |η| < 0.75, pT> 0.5 GeV/c At large forward rapidity range, azimuthal-angular independent pedestal component −> expected significant enhancement at central dAu collision

  27. Forward (Muon) – Mid rapdity, IdA d Au 1.4< η <2.0 -2 < η < -1.4 η < | 0.35| Phys.Rev.Lett.96:222301,2006 • No significant suppression or widening seen within large uncertainties! Only away side peak seen due to rapidity gap

  28. d Au Mid-Forward Correlations PHENIX central spectrometer magnet Muon Piston Calorimeter (MPC) p0s d xgluon ~ 10-2 (0.008,0.04) Au Forward direction (North)  Backward direction (South)  p0 or h+/- Side View

  29. Di-hadron Correlation, Mid-Fwd • Mid-rapidity triggered • Central d+Au collision shows suppression of away side peak • No away side peak width broadening apparent |hmid| < 0.35, hfwd = 3.0-3.8 |hmid| < 0.35, hfwd = 3.0-3.8 PRL107, 172301 (2011) • Normalized by pi0 triggers and subtracted uncorrelated background (b0) • Due to large rapidity separation, only away side peak is seen.

  30. Away side peak widths broadening ? Trigger p0: |h| < 0.35, 3.0 < pT < 5.0 GeV Trigger p0: |h| < 0.35, 2.0 < pT < 3.0 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)

  31. Mostly Merged p0s d Au Forward-Forward Correlations h1,2 = 3.4 PHENIX central spectrometer magnet Muon Piston Calorimeter (MPC) p0 clusters d Au xgluon ~ 10-4-10-3 (0.001, 0.005) Forward direction (North)  Backward direction (South)  Side View 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 hclus,p0 = 3.0-3.8 PRL107, 172301 (2011) • Normalized by pi0 triggers and subtracted uncorrelated background (b0, ZYAM) • Minimum cluster separation cut decrease amount of near side peak

  33. JdA (Mid-Fwd, Fwd-Fwd) PRL107, 172301 (2011) Note: points offset from true <Ncoll> to show pT dependence Suppression of JdA increases with Ncoll increase PTmid decrease PTfwddecrease Suppression of JdA increases with Ncoll increase Suppression Larger in fwd-fwd than mid-fwd Centrality dependent suppression

  34.  JdA Low x, mostly gluons JdA versus RGAu ? Eskola , Paukkunen, Salgado, JHP04 (2009)065 EPS09 NLO gluons Mid-Forward Forward-Forward RGAu b=0-100% Q2 = 4 GeV2 xAu arXiv:1109.2133v1 High x, mostly quarks Weak effects expected ~ RGAu

  35. Recent model predict “ Dihadron momentum imbalance and correlations in d+Aucollisions” Initial- and final-state multiple interactions can affect dijet(dihadron ) production in p+A(d+A) Zhong-Bo Kang, Ivan Vitev, Hongxi Xing et al, arXiv(1112.6021) dAu PHENIX JdA with model STAR Δϕ correlation with model This model explains both suppression and broadening of away side peak well.

  36. Summary • d+Au collision at forward rapidity range enables us to study low-x physics • PHENIX RdA , RCP 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 JdA ~ RGAU • Recent model calculation for both JdA and away side peak width

  37. Backup slide

  38. Nuclear Shadowing models N. ArmestoHep-ph/0604108v2

  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.

  40. PHENIX Muon Piston Calorimeter SOUTH North PbWO4 d(forward) Au(backward) • Fwd-Fwd, x~(0.001,0.005) • Mid-Fwd, x~(0.008,0.040) • Mid-Bwd, x~(0.050,0.100) Small cylindrical holes in Muon Magnet Pistons, Radius 22.5 cm and Depth 43.1 cm 40

  41. MPC Performance Jet1 Jet2 “Trigger” Near North MPC Far Decay photon impact positions for lowand high energy p0s. The decay photons from highenergy p0s merge into a single cluster Sometimes use (EM) clusters, but always corrected to 0 energy Clusters  80% 0 (PYTHIA)

  42. RCP and RdAu show strong rapidity dependence Brahms data Strong suppression at large rapidity (small-x) More central, larger rapidity range

  43. Quarkonia Suppression in A+A Collisions • Recent Gluon Saturation (CGC) calculations (arXiv:1109.1250v1) 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 ALICE y~3.2 PHENIX y=0 PHENIX y=1.7

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

  45. Yield Extraction Examples y>0, Centrality: 40-60 y>0, Centrality: 40-60 Estimated background rf w rf w Larger fitting range:0.4-2.6GeV Smaller parameter range Smaller fitting range:0.5-2.5 GeV Larger parameter range • Fitting function: Two Gaussian (f/w) + One Relativistc BW (r) +Background (Defined by estimated shape) • f yields stable when fitting procedure changes • r+wyields using background subtraction (large uncertainty)

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