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Cold Nuclear Matter Physics at Forward Rapidities from d+Au Collisions at PHENIX

Cold Nuclear Matter Physics at Forward Rapidities from d+Au Collisions at PHENIX. Mickey Chiu. PHENIX Muon Piston Calorimeter. SOUTH. North. PbWO 4. 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).

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Cold Nuclear Matter Physics at Forward Rapidities from d+Au Collisions at PHENIX

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  1. Cold Nuclear Matter Physics at Forward Rapidities from d+Au Collisions at PHENIX Mickey Chiu

  2. 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 2 QM2011 Annecy

  3. 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) QM2011 Annecy

  4. RdAu in 2 forward rapidity Bins Guzey, Strikman, Vogelsang, PL B603, 173 • Large suppression in RdA • That increases with centrality • And increases with larger rapidity • Consistent with previous measurements • However, x covered by single inclusive measurement is over wide range • Includes shadowing, anti-shadowing, (EMC effect) QM2011 Annecy Guzey, Strikman, Vogelsang, PLB603, 173

  5. RdA Past, di-Hadron Future CNM effects: dynamical shadowing, Energy Loss, Cronin Color Glass Condensate Kharzeev, NPA 748, 727 (2005) (Qiu, Vitev PLB632:507,2006) Kharzeev, Levin, McLerran  Nucl. Phys. A748 (2005) 627 • 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) QM2011 Annecy

  6. di-Hadron Signal Peripheral d+Au Correlation Function “ConditionalYield” • Number of di-jet particle pairsper trigger particle after corrections for efficiencies, combinatoric background, and subtracting off pedestal CORRELATED Npair Df “Di-Hadron Nuclear Modification factor” “Sgl-Hadron Nuclear Modification factor” • Possible indicators of nuclear effects • JdA < 1, RdA < 1 • Angular decorrelation of widths • Caveats: • 1. Low pT (but back-to-back peak is selected) • Pedestal Determination (Assumed up to twice the width as a systematic). • Di-Hadrons instead of di-jets (but ok if fragmentation unmodified) QM2011 Annecy

  7. p0 (trigger,central)/p0 (associate,forward) <pTa>=0.55 GeV/c <pTa>=0.77 GeV/c <pTa>=1.00 GeV/c 3.0 < pTt < 5.0 GeV/c for all plots p+p Correlation Function d+Au 60-88% d+Au 0-20% pTt, p0 Df PHENIX Preliminary pTa, p0 QM2011 Annecy

  8. Correlation Widths, d+Au and p+p 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) 8 No significant broadening between p+p and d+Au within large experimental uncertainties QM2011 Annecy

  9. JdA vs Ncoll, pTmid, pTfwd MPC p0 pT • Suppression of di-hadron correlation (relative to p+p binary scaling hypothesis) with Increasing Centrality Decreasing pTmid Decreasing pTfwd QM2011 Annecy

  10. pTt, p0 pTa, p0 Fwd-Fwd: p+p vs d+Au Peripheral Peripheral d+Au collisions are similar to p+p collisions Beam view of d+Au peripheral collision QM2011 Annecy

  11. pTt, p0 pTa, p0 Fwd-Fwd: p+p vs d+Au Central “Monojet” in central d+Au collisions Beam view of d+Au peripheral collision QM2011 Annecy

  12. MPC p0 pT JdA for Fwd-Fwd • Suppression of JdA gets larger in fwd-fwd correlations • Trend with pT, centrality also consistent with mid-fwd correlations (assuming LO) • Better way to plot: QM2011 Annecy

  13. xAufrag Dependence 60-88% (Peripheral) Trig pT: 1.1-5 GeV/c Trig pT: 0.5-7 GeV/c 0-20% (Central) Assoc pT: 0.5-1.5 GeV • Plotting vs suggests that the effect is due to something happening in the nucleus as one probes to lower x • Does it prove CGC? • Shadowing? Initial state energy loss? Multi-Parton Interactions (MPI)? Note: points for mid-fwd JdA are offset for visual clarity Statistical and systematic errors are added in quadrature QM2011 Annecy

  14.  JdA ~ RGAu Low x, mostly gluons Extending the LO picture Eskola , Paukkunen, Salgado, JHP04 (2009)065 EPS09 NLO gluons 60-88% (Peripheral) 0-20% (Central) b=0-100% Q2 = 4 GeV2 xAu High x, mostly quarks Weak effects expected QM2011 Annecy

  15. Backward (Au-going) MPC* d-going, low x Au-going, high x • Plotted vs IdA, but when factoring in RdA, this is a suppression of JdA in d-going, and enhancement in Au-going. • In anti-shadowing region? • Fwd-Bwd Correlations ( ~ 7): Future search for Mueller-Navelet Jets *See Z. Citron Poster QM2011 Annecy

  16. PRL 96:222301,2006 Summary • Large suppression (up to an order of magnitude) in FWD-FWD di-hadron yields in d+Au relative to p+p (JdA) • Suppression depends strongly on centrality • And gets stronger as both particles go toward more forward rapidities • Nuclear Shadowing? We see extreme Shadowing in most central. • Gluon Saturation/Color Glass Condensate? • Initial State Energy Loss? MPI? • Heavy Ion Physics is well into quantitative extraction of the properties of the sQGP • This requires careful control of all aspects of collisions (eg Initial State) • v2/v3, Initial State and /s • Talks by Shinichi Esumi, Roy Lacey • PHENIX Heavy Flavor Studies • Talks by Abhisek Sen, Cesar da Silva (Friday) • Angular Broadening of Away Side Jet? • Mid-Fwd, no increase seen within errors • Mid-MidFwd, also no increase • Fwd-Fwd, currently inconclusive • Future • Submitted to PRL, arxiv:nucl-ex/1105.5112 • Do di-Hadrons measure RGAu? • Better than incl. hadrons (EPS08) • p,n tagging, ’s, fwd-bwd, more d+Au running… QM2011 Annecy

  17. Backup Slides QM2011 Annecy

  18. IdA vs JdA: Can we decouple effects? • IdA is the per trigger comparison of d+Au jet associated counts relative to p+p • JdA is the rate of the associated pairs from a jet (per minbias event) • Can we use this to tell if the jets are modified, or do they disappear? • From the CNT-MPC corrrelations, we get IdA ~ 0.5, and RdA ~ 1.1 • JdA ~ 0.5 • The rate of correlated pairs is about half of p+p • Does this imply that the missing jets have disappeared, and not that they are modified, since IdA ~ JdA? • But not true for STAR FMS triggered-central barrel, where IdA ~ 1 and JdA ~ 0.5 QM2011 Annecy

  19. JdA, RdA vs Ncoll MPC p0 pT Qiu-Vitev Shadowing + Energy Loss (private communication) QM2011 Annecy

  20. Muon-Central IdA & Widths, 2003 d+Au d Au Phys.Rev.Lett.96:222301,2006 QM2011 Annecy

  21. Nuclear Modification in d+Au at Forward(Backward) Rapidity • Forward η suppression • No backward η suppression • Gluon Saturation? • Cronin, Shadowing, E-loss? • Look at 2 particle correlations … Punch through hadrons & Hadron decay muons 21 Phys. Rev. Lett. 94, 082302 (2005) QM2011 Annecy

  22. Run8 FMS p0+h± pT scan (inclusive) STAR Slide from A. Ogawa Const (BG) “gsv” pp Peak Area Peak Width dAu Df pT1 1.5 2.0 2.5 3.0 GeV/c pT2 0.5 1.0 1.5 2.0 GeV/c • dAu width larger than pp (consistent with FMS-BEMC results) • dAu back-to-back peak area larger than pp at lower pT • Work in progress towards even lower pT QM2011 Annecy

  23. Extended scaling? Fwd-Fwd? Fwd-Cnt? Where is the Saturation Scale if we are actually seeing the CGC? H. Kowalski and D. Teaney. Phys. Rev.D, 68:114005, 2003 Iancu and Venugopalan, hep-ph/0303204 • We evaluated in PYTHIA the ~ coverage for Q2 and x for the fwd-fwd and cnt-fwd correlations • No nuclear modifications evaluated yet • Not clear that we are in the saturation region – possibly in extended region? • Can we determine Qs from the data? • Go to lower pt, but then background becomes worse • Nuclear Scaling: QM2011 Annecy

  24. Fwd-Fwd Near Side Correction Jet1 Jet2 Points affected by pair cuts (and hence merging effects in clustering) “Trigger” Near North MPC Far 24 QM2011 Annecy

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