Results on deuteron – gold collision at forward rapidity in PHENIX IhnJea Choi (UIUC) For the PHENIX collaboration 01/04/2012 1/4/12 HEP2012@Chile

Outline d+Au collision Experiment 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 1/4/12 HEP2012@Chile

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)? Backward rapidity (Au going direction) x_Au > x_d 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) 1/4/12 HEP2012@Chile

Why hadron production suppressed at forward rapidity ! Nuclear Modification factor Cold Nuclear Matter(CNM) effect STAR, BRAHMS Forward h PRL 97 (2006), 152302 p0 meson PHENIX |h| < 0.35 RdA RdA ~ 1 at mid rapidity PRL 98 (2007), 172302 STAR BRAHMS results show RdA < 1 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. 1/4/12 HEP2012@Chile

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 Mechanism for gluon saturation RpA suppressed at all values of pT as rapidity / energy grows. 1/4/12 HEP2012@Chile

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 Energy loss of incident gluon shifts effective xF and produces nuclear suppression which increases with xF R(A/p) R=1 xF A p Absorption (or dissociation) of into two D mesons by nucleus or co-movers 1/4/12 HEP2012@Chile

RHIC Completed as of 2006 STAR 1/4/12 HEP2012@Chile

RHIC Luminosity Run3 d+Au 2.74 nb-1 MB triggered 1/4/12 HEP2012@Chile

PHENIX Detector 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 Muon Arms 1.2 < | η | < 2.4 Heavy Flavor muons J/Psi Charged hadrons Installed 2005-7 1/4/12 HEP2012@Chile

PHENIX Muon Piston Calorimeter (MPC) 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 p0gg Merged p0gg 1/4/12 HEP2012@Chile 10

Single hadron results 1/4/12 HEP2012@Chile

Punch Through Hadron & Hadron Decay Muon RCP Phys. Rev. Lett. 94, 082302 (2005) Mostly π+-,Κ+- and their decay into μ+- Forward rapidity suppression No backward rapidity suppression (slightly enhanced) Consistent result with BRAHMS results ( η = 2.2 ) 1/4/12 HEP2012@Chile 12

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 1/4/12 HEP2012@Chile 13

CNM effects in J/ψ production PHENIX arXiv:1010.1246v1 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. Gluon saturation model is good agreement with data at forward rapidity. 1/4/12 HEP2012@Chile

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) 1/4/12 HEP2012@Chile

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? ) 1/4/12 HEP2012@Chile

Forward π0 results for RdA PHENIX MPC Suppression increase with increasing rapidity and centrality 1/4/12 HEP2012@Chile

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 1/4/12 HEP2012@Chile

Di-hadron correlation 1/4/12 HEP2012@Chile

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 ! 1/4/12 HEP2012@Chile

Di-hadron azimuthal angle correlation Measure Df of all particle pairs trigger particle (usually leading pT) associate particle (lower pT) trigger associate Df Beam view or transverse plane p+p, d+Au di-hadron correlations are similar at mid rapidity Dh=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 Df Nearside peak Beam View Df Awayside Peak 1/4/12 HEP2012@Chile

CY / IdA / JdA Df CY ( Conditional Yield ) CORRELATED Npair CY ( Conditional Yield ) Number of particle pairs per trigger particle after corrections for efficiencies, combinatoric background, and subtracting off pedestal. Df Trigger comparison of d+Au jet associated counts relative to pp Di-Hadron pair Nuclear Modification factor Single hadron Nuclear Modification Factor 1/4/12 HEP2012@Chile

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) 162301 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 HEP2012@Chile

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 1/4/12 HEP2012@Chile

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) 1/4/12 HEP2012@Chile

Dihadron, Multi Parton Interaction(MPI) PRD 83, 034029 M. Strikman, W. Vogelsang STAR 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 1/4/12 HEP2012@Chile

Forward (Muon) – Mid rapdity, IdA Au d -2 < η < -1.4 1.4< η <2.0 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 1/4/12 HEP2012@Chile

Mid-Forward Correlations p0s p0 or h+/- PHENIX central spectrometer magnet Muon Piston Calorimeter (MPC) d Au d Au xgluon ~ 10-2 (0.008,0.04) Forward direction (North)  Backward direction (South)  Side View 1/4/12 HEP2012@Chile

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 Normalized by pi0 triggers and subtracted uncorrelated background (b0) Due to large rapidity separation, only away side peak is seen. PRL107, 172301 (2011) 1/4/12 HEP2012@Chile

Away side peak widths broadening ? Trigger p0: |h| < 0.35, 2.0 < pT < 3.0 GeV Trigger p0: |h| < 0.35, 3.0 < pT < 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 HEP2012@Chile

Forward-Forward Correlations h1,2 = 3.4 Mostly Merged p0s clusters p0 PHENIX central spectrometer magnet Muon Piston Calorimeter (MPC) d Au d Au xgluon ~ 10-4-10-3 (0.001, 0.005) Forward direction (North)  Backward direction (South)  Side View 1/4/12 HEP2012@Chile 31

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 1/4/12 HEP2012@Chile

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 PT mid decrease PT fwd decrease Suppression of JdA increases with Ncoll increase Suppression Larger in fwd-fwd than mid-fwd Centrality dependent suppression 1/4/12 HEP2012@Chile

JdA versus RGAu ? EPS09 NLO gluons RGAu xAu  JdA  ~ RGAu b=0-100% Forward-Forward Mid-Forward b=0-100% Q2 = 4 GeV2 xAu EPS09 NLO gluons Eskola , Paukkunen, Salgado, JHP04 (2009)065 RGAu arXiv:1109.2133v1 Low x, mostly gluons  JdA  High x, mostly quarks Weak effects expected ~ RGAu 1/4/12 HEP2012@Chile

Recent model predict “ 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) 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. 1/4/12 HEP2012@Chile

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 1/4/12 HEP2012@Chile

Backup slide 1/4/12 HEP2012@Chile

Nuclear Shadowing models N. Armesto Hep-ph/0604108v2 1/4/12 HEP2012@Chile

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 HEP2012@Chile

PHENIX Muon Piston Calorimeter d(forward) Au(backward) North SOUTH Add d, Au cartoon, define forward, mid, backward Fwd-Fwd, x~(0.001,0.005) Mid-Fwd, x~(0.008,0.040) Mid-Bwd, x~(0.050,0.100) PbWO4 Small cylindrical holes in Muon Magnet Pistons, Radius 22.5 cm and Depth 43.1 cm 1/4/12 HEP2012@Chile 40

MPC Performance North MPC “Trigger” Near North MPC Far Jet1 Jet2 Decay photon impact positions for low and high energy p0s. The decay photons from high energy p0s merge into a single cluster Sometimes use (EM) clusters, but always corrected to 0 energy Clusters  80% 0 (PYTHIA) MPC Performance Proof, Explanation of merging at “low” pt 1/4/12 HEP2012@Chile

RCP and RdAu show strong rapidity dependence Brahms data Strong suppression at large rapidity (small-x) More central, larger rapidity range 1/4/12 HEP2012@Chile

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 1/4/12 HEP2012@Chile

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. 1/4/12 HEP2012@Chile

Yield Extraction Examples Fitting function: Two Gaussian (f/w) + One Relativistc BW (r) +Background (Defined by estimated shape) f yields stable when fitting procedure changes r+w yields using background subtraction (large uncertainty) y>0, Centrality: 40-60 y>0, Centrality: 40-60 Estimated background r f w r f w Larger fitting range:0.4-2.6GeV Smaller parameter range Smaller fitting range:0.5-2.5 GeV Larger parameter range 1/4/12 HEP2012@Chile