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Forward (onium) physics from PHENIX

Forward (onium) physics from PHENIX. Mickey Chiu. Why are we interested?. as. High energy behavior might be universal across all hadrons and predicted entirely by the CGC. CGC:. x < 10 -2. Geometric Scaling Strongly coupled regime which becomes classical  computable!.   0.3.

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Forward (onium) physics from PHENIX

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  1. Forward (onium) physics from PHENIX Mickey Chiu

  2. Why are we interested? as • High energy behavior might be universal across all hadrons and predicted entirely by the CGC CGC: x < 10-2 • Geometric Scaling • Strongly coupled regime which becomes classical  computable!  0.3

  3. CGC in Heavy Ion Collisions W=200 GeV PHOBOS • As Initial state for Heavy Ion Collisions • Multiplicity Distributions • Long range correlations from a “glasma”, explanation of the ridge But the outstanding question is, do we see the CGC at RHIC?

  4. Expectations for a color glass condensate t related to rapidity of produced hadrons. Kharzeev, Kovchegov, and Tuchin, hep-ph/0307037 As y grows Iancu and Venugopalan, hep-ph/0303204 Are the forward d+Au results evidence for gluon saturation at RHIC energies? Not clear. Need more data, and more observables.

  5. 22 Hard Scattering (LO) p3 Initial State: p2 p1 Final State: P=s/2 P p4 Simply Elastic Scattering Special Cases: a. y3 forward, y4 mid-rapidity (MPC-EMC) b. y3, y4 both forward (MPC-MPC) a. y3 forward, y4 backwards (MPC.S-MPC.N)

  6. PHENIX Muon Piston Calorimeter PbWO4 Density 8.28 g/cm3 Size 2.2x2.2x18 cm3 Length 20 X0, 0.92  Weight 721.3 g SOUTH NORTH Moliere radius 2.0 cm Radiation Length 0.89 cm Interaction Length 22.4 cm Light Yield ~10 p.e./MeV @ 25 C Temp. Coefficient -2% / C Radiation Hardness 1000 Gy Main Emission Lines 420-440, 500 nm Refractive Index 2.16 Small cylindrical hole in Muon Magnet Piston, Radius 22.5 cm and Depth 43.1 cm 6 Color Glass Condensate Workshop, RHIC-AGS 2009

  7. MPC MPC PHENIX Acceptance South Muon Tracker North Muon Tracker EMCAL + Central Tracker 0 f coverage 2p EMCAL + Central Tracker -3 -2 -1 0 1 2 3 rapidity • Addition of MPC increases PHENIX acceptance for calorimetry by a factor of 4 (with a detector more than 10 times smaller) • Especially important that the very forward region (>3) is covered 7 Color Glass Condensate Workshop, RHIC-AGS 2009

  8. PHENIX Side View PHENIX central spectrometer magnet Muon Piston Calorimeter (MPC) Muon Piston 8 Color Glass Condensate Workshop, RHIC-AGS 2009

  9. Forward/Central Correlation PHENIX central spectrometer magnet Muon Piston Calorimeter (MPC) d p0, or clusters Au Backward direction (South)  Forward direction (North)  p0 or h+/- 9 Color Glass Condensate Workshop, RHIC-AGS 2009

  10. The MPC can reliably detect pions (via p0g g) up to 17 GeV in energy Limitations are the tower separation and merging effects  pT max ~ 1.7 GeV/c To go to higher pT, use single clusters in the calorimeter Use p0s for 7 GeV < E < 17 GeV Use clusters for 20 GeV < E < 50 GeV Correlation measurements are performed using p0s, clusters Use event mixing to identify pions  form foreground (same event pairs) and mixed event background photon pair distributions MPC Pion/Cluster Identification North MPC Foreground 12 < E < 15 Background Yield Minv (GeV/c2) 10 Color Glass Condensate Workshop, RHIC-AGS 2009

  11. Correlation Measurements sNN = 200 GeV d-Au, pp collisions from 2008 at RHIC No flow contribution Rapidity separated jets produce no nearside peak  Constant background + Gaussian signal Trigger particles are (p0, h+/-) with |h| < 0.35 Associate particles are p0, clusterswith 3.1 < h < 3.9 One method to quantify the correlation: To compare pp with dA, form ratio of conditional yields Peripheral d-Au Correlation Function Npair Df 11 Color Glass Condensate Workshop, RHIC-AGS 2009

  12. h+/- (trigger,central)/p0 (associate,forward) <pTa>=0.55 GeV/c <pTa>=0.77 GeV/c <pTa>=1.00 GeV/c 1.0 < pTt < 2.0 GeV/c for all plots pp Correlation Function dAu 0-20% dAu 60-88% pTt, h+/- Df pTa, p0 12 Color Glass Condensate Workshop, RHIC-AGS 2009

  13. p0 (trigger,central)/p0 (associate,forward) <pTa>=0.55 GeV/c <pTa>=0.77 GeV/c <pTa>=1.00 GeV/c 2.0 < pTt < 3.0 GeV/c for all plots pp Correlation Function dAu 0-20% dAu 60-88% pTt, p0 Df pTa, p0 13 Color Glass Condensate Workshop, RHIC-AGS 2009

  14. p0 (trigger,central)/cluster (associate,forward) <pTa>=1.09 GeV/c <pTa>=2.00 GeV/c <pTa>=3.10 GeV/c 2.0 < pTt < 3.0 GeV/c for all plots pp Correlation Function dAu 0-20% dAu 60-88% pTt, p0 Df pTa, cluster 14 Color Glass Condensate Workshop, RHIC-AGS 2009

  15. Forward/Central Correlation Widths No significant changes in correlation width between pp and dAu within experimental uncertainties Trigger p0: |h| < 0.35, 3.0 < pT < 5.0 GeV/c Trigger p0: |h| < 0.35, 2.0 < pT < 3.0 GeV/c dAu 0-20% pp dAu 40-88% 15 Color Glass Condensate Workshop, RHIC-AGS 2009

  16. Forward/Central IdA vs Ncoll Increasing suppression of IdA reaches a factor 2 for central events Model calculations are needed to distinguish between different models Saturation (Color Glass Condensate) Shadowing Cronin Others? Associate p0: 3.1 < h< 3.9, 0.45 < pT < 1.59 GeV/c 16 Color Glass Condensate Workshop, RHIC-AGS 2009

  17. Muon-Central IdA & Widths, 2003 d+Au d Au Phys.Rev.Lett.96:222301,2006 Color Glass Condensate Workshop, RHIC-AGS 2009

  18. d+Au RCP, 1.2<||<2.2 PHENIX 2003 d+Au RHIC experiments have observed a suppression of hadron production relative to binary collision scaling in deuteron-gold reaction at forward rapidity sensitive to low x partons in the gold nucleus, Phys.Rev.Lett.94:082302,2005). Color Glass Condensate Workshop, RHIC-AGS 2009

  19. 19 Kopeliovich, hep-ph/0501260v3 Universal Sudakov suppression (energy conservation) Vitev, hep-ph/0405068v2 Dynamical shadowing Vitev, hep-ph/0605200v1 CNM effects: dynamical shadowing, dE/dx, Cronin Kharzeev, NPA 748, 727 (2005) Color Glass Condensate Workshop, RHIC-AGS 2009

  20. Rapidity-separated hadron correlations in d+Au • At least two kinds of effects may give suppression in pairs that include a forward rapidity wrt mid-rapidity trigger hadron shadowing (non-LT) gives suppression of pairs wrt to singles for mid-rapidity tag – but small for forward tag Vitev, hep-ph/0405068v2 shadowing (non-LT) gives suppression of pairs wrt to singles for mid-rapidity tag – but small for forward tag Vitev, hep-ph/0405068v2 Mono-jets in the gluon saturation (CGC) picture give suppression of pairs per trigger and some broadening of correlation Kharzeev, NPA 748, 727 (2005) Dilute parton system (deuteron) PT is balanced by many gluons Dense gluon field (Au) Color Glass Condensate Workshop, RHIC-AGS 2009

  21. Shadowing & the EMC effect • depletion at small-x • enhancement (anti-shadowing) at larger-x • EMC effect at large x • Fermi motion near x~1 • Either from global fits to deep-inelasitic scattering and Drell-Yan data • e.g. Eskola – EPS09 • arXiv:0902.4154 • Or from coherence models • e.g. Vitev • hep-ph/0309094 Color Glass Condensate Workshop, RHIC-AGS 2009

  22. Vogt EKS Phys Rev C77, 024912 Extrinsic EKS 0809.4684v1 • 2003 PHENIX d+Au published J/Psi RdAu • Production model makes a difference. QM09 Knoxville TN 9/4/2014 22 Color Glass Condensate Workshop, RHIC-AGS 2009

  23. 23 Quarkonia Production & Suppression – J/Ψ in d+Au • Initial d+Au J/Ψ update from new 2008 data (~30x 2003) • RCP pretty flat vs centrality at backward rapidity; but falls at forward rapidity (small-x) • more soon – precision statistics requires precision systematics & careful analysis • starting to study constraints on CNM models (thanks R. Vogt) EKS σ = 0,1,2,3,4,…15 EKS σ = 0,1,2,3,4,…15 Color Glass Condensate Workshop, RHIC-AGS 2009

  24. Conclusions • Forward Pion I_dA for Central Arm Triggered hadrons – forward MPC pi0’s • Widths ~ consistent between p+p and d+Au • Associated Yields suppressed in d+Au, and stronger with more central collisions • Working on triggered MPC data and Au going MPC side • Can then map out x dependence • Less forward muon arm triggered (2-5 GeV pT) hadrons – central arm hadron correlations show small I_dAu difference • R_dAu of those muon arm hadrons shows suppression pattern • New data from run08 on the way • Some of the more “ordinary” cold nuclear effects can be mapped out with complementary measurements, like J/Psi. • d+Au is a very complicated system Color Glass Condensate Workshop, RHIC-AGS 2009

  25. Backup Slides Color Glass Condensate Workshop, RHIC-AGS 2009

  26. Color Glass Condensate Workshop, RHIC-AGS 2009

  27. 27 Brief PHENIX Status & Future • Recent detector improvements: • large, more accurate reaction plane detector • higher-pT PID (TOF-West) • forward (MPC) calorimeters • Hadron blind detector (HBD) • Operations improvements: • integrated luminosity: Au+Au (x3); d+Au (x30) • data taking efficiency: 52% (2007) -> 68% (2008) • Future: • HBD for clean low-mass dielectron measurements (next AuAu run) • muon Trigger system for high-pT muon triggering (W’s) • silicon detectors for new level of robustness in heavy-quark measurements • continuing DAQ upgrades to maintain high speed and efficiency HBD MPC VTX/FVTX Color Glass Condensate Workshop, RHIC-AGS 2009

  28. LHC: extending the low-x reach • RHIC as opened the low-x frontier finding indications for new physics (CGC?) • LHC will lower the x- frontier by another factor ~30 at the same rapidities Color Glass Condensate Workshop, RHIC-AGS 2009

  29. 29 Cold Nuclear Matter (CNM) & Gluon Saturation hep-ph/0902.4154v1 RGPb Traditional shadowing or coherence models Gluon saturation at small x; amplified in a nucleus Initial state energy loss & multiple scattering Color Glass Condensate Workshop, RHIC-AGS 2009 Mike Leitch - PHENIX

  30. Experimental Method: Overview Using azimuthal angle two-particle correlation technique d+Au, pp collisions at sNN= 200 GeV from RHIC Run8 Rapidity separated particles with one particle in the forward direction allows one to probe the gluon distribution at lower x Trigger particles are (p0, h+/-) with |h| < 0.35 Associate particles are forward p0s and clusters with 3.1 < h < 3.9 Central Rapidity Spectrometer π0 3.1 < η < 3.9 Forward EMC π0 x-range in Au: 0.006 < x < 0.1 From calculation by Marco Stratmann 30 Color Glass Condensate Workshop, RHIC-AGS 2009

  31. Any difference between p+p and d+Au? p+p: Di-jet d+Au: Mono-jet? Dilute parton system (deuteron) PT is balanced by many gluons Dense gluon field (Au) Kharzeev, Levin, McLerran(NPA748, 627) Color glass condensate predicts that the back-to-back correlation from p+p should be suppressed Color Glass Condensate Workshop, RHIC-AGS 2009

  32. PRL 94, 082302 PRL 96, 222301 STAR Forward-midrapidity correlations in d+Au PRL 97, 152302 • PHENIX doesn’t see any changes for <xg> ~ 0.015 • STAR might see suppression for <xg> ~ 0.006 π0:|<η>| = 4.0 h±: |η| < 0.75 pT > 0.5 GeV/c Color Glass Condensate Workshop, RHIC-AGS 2009

  33. Cold Nuclear Structure (d+Au) Observation that structure functions are altered in nuclei stunned much of the HEP community ~25 years ago Regions of: • Fermi smearing • EMC effect • Enhancement • Shadowing • Saturation? Regions of shadowing and saturation mostly around Q2 ~1 GeV2 F2D/F2A

  34. Saturation picture in nuclei Relativistic proton picture (In rest frame of proton) Nucleus picture • Transverse area of a parton ~ 1/Q2 • Cross section parton-probe : s~ as/Q2 • Partons start to overlap when SA~NAs • The parton density saturates • Saturation scale : Qs2 ~ as(Qs2)NA/pRA2 ~A1/3 • At saturation Nparton is proportional to 1/as • Qs2 is proportional to the density of participating nucleons; larger for heavy nuclei.

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