Hadron Physics at RHIC o RHIC Physics o Low x  Saturation? o Access to Nucleon Structure? pQCD vs Experiment o Proton Spin Structure RHIC and Experiments Gluon Spin Transverse Spin STAR pp2pp M. Grosse Perdekamp UIUC and RBRC Observables in Antiproton-Proton Interactions and their Relevance to QCD

Hadron Physics at RHIC2 July 6 th Physics at the Relativistic Heavy Ion Collider o Quark Matter at high Temperatures and Densities ion-ion collisions (Cu-Cu, Au-Au: √s NN =22.5, 62, 130, 200 GeV) o Proton Spin Structure polarized proton-proton collisions (p-p: √s=200 to 500 GeV) o Low-x and high parton densities ion-deuteron collisions (d-Au: √s NN =200 GeV) very active field: eg. 76 Physical Review Letters in the first 5 years with more than 6800 citations in SPIRES

Hadron Physics at RHIC3 July 6 th available channels jets, hadrons, photons, photon-jet, heavy flavor Single spin lepton asym- metries in W-production, Lambda production (1) A N (2) A TT in Collins- and Interference-Fragmentation (3) A TT and A T In Drell Yan goals determine first moment of the spin dependent gluon distribution. flavor separation of quark and anti-quark spin distributions measurement of trans- versity and Sivers distributions Proton Spin Structure in Polarized p-p Collisions at RHIC

Hadron Physics at RHIC4 July 6 th Structure of Neutron Stars  physics goal to find quark matter and survey it’s properties experimental method heavy ion collisions at high energies Heavy Ion Physics

Hadron Physics at RHIC5 July 6 th Heavy Ion Physics A brief history of Heavy Ion Experiment Bevalac AGS GSI SPS RHIC LHC Find quark matter and survey it’s properties

Hadron Physics at RHIC6 July 6 th RHIC 2001 – 2005 : the sQGP ! Key Observations 1.Jets are suppressed in central Au + Au collisions –Suppression is flat up to p t ~ 10 GeV/c –Absence of suppression in d+Au 2. Strong elliptic flow –Scaling of v 2 with eccentricity shows that a high degree of collectivity builds up at a very early stage of collision – evidence for early thermalization –Data described by ideal hydrodynamic models  fluid description of matter applies. 3.Energy density allows for a non-hadronic state of matter –Energy density estimates from measurements of dN/dy are well in excess of the ~1 GeV/fm 3 lattice QCD prediction for the energy density needed to form a deconfined phase. Strongly interacting Quark Gluon Plasma !

Is the Initial State in Heavy Ion Collisions Determined by Saturation Effects in the Gluon Field ?

Hadron Physics at RHIC8 July 6 th BRAHMS, PRL 93, and R. Debbe R dAu = Y dAu N coll Y pp BRAHMS d+Au Results as Function of Rapidity and Centrality Hadron production is suppressed at large rapidity consistent with saturation effects at low x in the Au gluon densities  CGC

Hadron Physics at RHIC9 July 6 th PRL 94, Suppression in the d direction and enhancement in the Au frag. region Similar Effects Seen by PHENIX and PHOBOS

Hadron Physics at RHIC10 July 6 th Saturation Picture (CGC) Consistent with Data A. Dumitriu et al. Nucl. Phys. A ,2006 Not bad! However, Large K factors, η-dependent. We hope for NLO calculations soon …

Access to Nucleon Structure in Hadron Collisions?

Hadron Physics at RHIC12 July 6 th Access to Nucleon Structure at RHIC Measure: (spin dependent) cross sections QCD analysis: (spin dependent) distribution functions

Hadron Physics at RHIC13 July 6 th Example:  G(x) from global NLO pQCD analysis using projected future direct photon data from RHIC M. Hirai, H.Kobayashi, M. Miyama et al. (Asymmetry Analysis Collaboration) QCD analysis of inclusive DIS data QCD analysis DIS data + future direct photons

Hadron Physics at RHIC14 July 6 th M. Hirai, H.Kobayashi, M. Miyama et al. (Asymmetry Analysis Collaboration) Does NLO pQCD provide a reliable framework for the interpretation of polarized proton data in terms of polarized parton distribution functions? QCD analysis of inclusive DIS data QCD analysis DIS data + future direct photons Example: ΔG(x) from global NLO pQCD analysis using projected future direct photon data from RHIC

Hadron Physics at RHIC15 July 6 th I) Tevatron data as input to CTEQ QCD analysis of hard scattering data, specifically: G(x,Q 2 ) II) Comparison: NLO pQCD vs RHIC data  inclusive hadrons  inclusive jets  direct photons Is pQCD applicable in p-p Collisions ?

Hadron Physics at RHIC16 July 6 th CTEQ Global QCD Analysis for G(x,Q 2 ) and q(x,Q 2 ) J. Pumplin et.al JEHP 0207:012 (2002) x gluon down up-quarks anti-down Quark and Gluon Distributions error on G(x,Q 2 ) error for u(x,Q 2 ) +/- 10% +/- 5% error for d(x,Q 2 ) x CTEQ6: use DGLAP Q 2 -evolution of quark and gluon distributions to extract q(x,Q 2 ) and G(x,Q 2 ) from global fit to data sets at different scales Q 2. H1 + Zeus F 2 CDF + D0 Jets CTEQ5M1 CTEQ6M

Hadron Physics at RHIC17 July 6 th G(x,Q 2 ) and q(x,Q 2 ) + pQCD beautifully agree Tevatron + HERA! J. Pumplin et.al JEHP 0207:012 (2002) D0 Jet Cross Section ZEUS F 2

Hadron Physics at RHIC18 July 6 th Data vs NLO pQCD at RHIC: Inclusive π 0 PHENIX π 0 cross section a |η|<0.35 Phys.Rev.Lett.91:241803,2003 STAR π 0 cross section a 3.4<η<4.0 Phys.Rev.Lett.92:171801,2004 NLO QCD from W. Vogelsang

Hadron Physics at RHIC19 July 6 th Theory calculation show good agreement with the experimental cross section. Direct Photons and Inclusive Jets vs NLO pQCD Inclusive Jet Cross sectionDirect Photon Cross section STAR Preliminary PHENIX Preliminary NLO QCD from W. Vogelsang NLO QCD from W. Vogelsang

Hadron Physics at RHIC20 July 6 th Direct Photons in Heavy Ion Collisions Use hard probes (hadrons vs direct photons) to study medium formed in heavy ion collisions at RHIC q g direct photon quark  jet

Hadron Physics at RHIC21 July 6 th 15 fm b 0 fm 0 N part 394 Spectators Participants N part ~ (No. participants) N binary ~ (No. binary collisions) Collision Geometry: Impact Parameter vs Collisions and Participants 0 N binary 1200

Hadron Physics at RHIC22 July 6 th pQCD vs Direct Photons in Au+Au PRL 94, pQCD x number of binary nucleon-nucleon collisions, N binary, in heavy in collisions (Werner Vogelsang) pQCD calculations permit “calibration” of hard probes in heavy ion collisions at RHIC in a model indepen- dent way

Hadron Physics at RHIC23 July 6 th pQCD vs Inclusive Hadrons: “ Jet Suppresion ” Suppression is strong (factor 5) up to 20 GeV/c Medium is extremely opaque The data provide a lower bound on the initial gluon density pp comparison data (and pQCD!)

RHIC

Hadron Physics at RHIC25 July 6 th RHIC: ion-ion and polarized p-p Collider

Hadron Physics at RHIC26 July 6 th RHIC  five complementary experiments pp2pp

Hadron Physics at RHIC July 6 th AGS LINAC BOOSTER Polarized Source Spin Rotators Partial Snake Siberian Snakes 200 MeV Polarimeter AGS Polarimeter Rf Dipole RHIC pC Polarimeters Absolute Polarimeter (H jet) P HENIX P HOBOS B RAHMS & PP2PP S TAR Siberian Snakes Helical Partial Snake Strong Snake Spin Flipper 2005 Complete! A novel experimental method A novel experimental method: Probing Proton Spin Structure Through High Energy Polarized p-p Collisions high current polarized source high energy proton polarimetry helical dipoles magnets Run 2006 ∫Ldt ~ 23.5 pb -1 Polarization average 60%

Hadron Physics at RHIC28 July 6 th 2006: Figure of Merit Goals and Actual P 2 L: Transverse P 4 L: Longitudinal ~7 times Run-5 goals

Hadron Physics at RHIC29 July 6 th 100% transverse spin! Two spectrometer arms with good particle ID at high momenta BRAHMS: A N for charged π,K, p, low x

Hadron Physics at RHIC30 July 6 th PHENIX: ∆G, ∆q/∆q, Sivers, δq, low x Muon ID Panels Central Arms North Muon Arm South Muon Arm Ring Imaging Cerenkov EM Calorimeter Muon Tracking Chambers Beam-Beam Counter Multiplicity/Vertex Detector Time Expansion Chamber Drift Chambers Pad Chambers Time of Flight Panels Four spectrometer arms with excellent trigger and DAQ capabilities.

Hadron Physics at RHIC31 July 6 th STAR: ∆G, ∆q/∆q, Sivers, δq, low x Large acceptance TPC and EMC -1<η<2

Hadron Physics at RHIC32 July 6 th RHIC Detector Status and Upgrades o All instrumentation is in place for the planned measurements on spin dependent gluon distributions and transverse spin. o W-physics (flavor separation of quark and anti-quark polarizations) requires upgrades in PHENIX (muon trigger, funded by NSF and JSPS) and STAR (forward tracking, grant proposal to DOE in preparation). o In PHENIX a central silicon tracking upgrade and a forward tungsten silicon calorimeter upgrade will significantly enhance capabilities for jet and photon-jet physics. o A RHIC luminosity upgrade (RHIC II) for heavy ions with electron cooling will gain a factor 3-5 (beyond design) in luminosity from 2012.

Gluon Spin Distribution A LL in inclusive Jets (STAR) A LL for inclusive π 0 (PHENIX)

Hadron Physics at RHIC34 July 6 th  Results limited by statistical precision  Total systematic uncertainty ~0.01 (STAR) + beam pol. (RHIC)  GRSV-max gluon polarization scenario disfavored jet cone=0.4 *) Predictions: B.Jager et.al, Phys.Rev.D70(2004) A LL from Inclusive Jets in p+p Collisions at √s=200GeV STAR Preliminary STAR Projections for 2006

Hadron Physics at RHIC35 July 6 th Run 5 A LL (   ): First constraints for ∆G(x) Comparison with ∆G from QCD analysis of DIS data: M. Glück, E. Reya, M. Stratmann, and W. Vogelsang, Phys. Rev. D 53 (1996) ¨ standard ∆G from DIS ∆G =0 max ∆G from DIS min ∆G possible Excludes large gluon spin contributions! Needs to be quantified with NLO pQCD analysis! 40% scale error (missing abso- lute polarization measurement).

Hadron Physics at RHIC36 July 6 th NLO QCD Analysis of DIS A 1 + A LL (π 0 ) M. Hirai, S. Kumano, N. Saito, hep-ph/ (Asymmetry Analysis Collaboration) DIS A 1 + A LL (π 0 ) ACC03 x

Hadron Physics at RHIC37 July 6 th  Final results on ∆G will come from combined NLO analysis of all channels at RHIC and in DIS  RHIC measurements will span broad range in x with good precision. multiple channels with independent theo. and exp. uncertainties.  Uncertainty through extrapolation to small x  s=200 GeV incl.  0 prod’n  s=500 GeV incl. jet prod’n ∆G Measurements by 2012 see Spin report to DOE

Transverse Spin A N for inclusive hadrons (BRAHMS, PHENIX, STAR)

Hadron Physics at RHIC39 July 6 th QCD Cross Sections for Transverse Spin QCD: Asymmetries for transverse spin are small at high energies (Kane, Pumplin, Repko, PRL 41, 1689–1692 (1978) ) QCD Test !

Hadron Physics at RHIC40 July 6 th QCD Cross Sections for Transverse Spin QCD: Asymmetries for transverse spin are small at high energies (Kane, Pumplin, Repko, PRL 41, 1689–1692 (1978) ) π+π+ π-π- π0π0 Suggestions: Sivers-, Collins-, Qui-Sterman, Koike mechanisms !? Experiment (E704, Fermi National Laboratory): Can QCD be re-conciled with large transverse asymmetries?

Hadron Physics at RHIC41 July 6 th A N Results from PHENIX and STAR PHENIX A N (π 0 ) and A N (π 0 ) at |η|<0.35 Phys.Rev.Lett.95:202001,2005 STAR A N (π 0 ) at 3.4<η<4.0 Phys.Rev.Lett.92:171801,2004 and (hep-ex/ ) Sizable asymmetries for x F > 0.4 Back angle data consistent with A N ~ 0

Hadron Physics at RHIC42 July 6 th   K+K+ K-K- BRAHMS A N Pions Kaons Protons p p  DIS 2006, prel. stat. errors only  First A N for kaons and protons  A N (K - ) and A N (p) don’t agree with naive expectation from valence quark fragmentation

Hadron Physics at RHIC43 July 6 th A N : Maximum Asymmetries Possible (II) Transversity quark-distributions and Collins fragmentation Correlation between proton- und quark-spin and spin dependent fragmentation (I) Sivers quark and gluon distributions Correlation between proton-spin and transverse quark momentum M. Anselmino, M. Boglione, U. D’Alesio, E. Leader, S. Melis and F. Murgia hep-ph/ quark-Sivers gluon-Sivers Transversity x Collins RHIC 2006: precision measurements of A N with ~ 20 x ∫Ldt and 2-3 x P beam on tape:  QCD analysis to separate effects !?

Hadron Physics at RHIC44 July 6 th Measurement of Transversity- and Sivers- Distributions in Polarized p-p Collisions at RHIC A N excellent! A N (jet/hadron-correlations) good (Sivers signature!) A T (Collins FF) just enough A T (Interference FF) just enough A T (Drell Yan) no A TT ( Drell Yan) no RHIC Luminosity? RHIC II Luminosities requires Collins and Interference FFs  e + e - at Belle

Hadron Physics at RHIC45 July 6 th Transversity : correlation between transverse proton spin and quark spin Sivers : correlation between transverse proton spin and quark transverse momentum Boer/Mulders: correlation between transverse quark spin and quark transverse momentum RHIC II Luminosity Upgrade Transversity & Sivers & Boer-Mulders in Drell Yan

Hadron Physics at RHIC46 July 6 th Sivers-Asymmetries, A T in Drell Yan (J. Collins et al.) STAR for 125pb -1 Dedicated DY Experiment 1250 pb -1 o 10 o’clock  100% transverse polarization o mini-quads o acceptance: -3 < η < 3 ATAT Q=4GeV Q=20GeV Q=4GeVQ=20GeV ATAT

Hadron Physics at RHIC47 July 6 th Transversity in Drell Yan with a Dedicated Drell Yan Experiment for Transverse Spin A TT for Drell Yan with dedicated DY detector projections for 1250pb -1 of running, 5-10% higher polarization, with RHIC II luminosities and large acceptance Drell Yan 1.25fb -1, large acceptance detector for Drell Yan This measurement appears to be also possible at 500 GeV

Hadron Physics at RHIC48 July 6 th Summary RHIC and it’s experiments are the world’s first facility capable of colliding high energy polarized protons and heavy ions. Collider and Experiments are complete and first high statistics polarized proton runs took place in 2005 and Hadron Collisions at RHIC provide a powerful experimental tool to study the structure of the nucleon. We are at the beginning of a broad new program on spin dependent nucleon substructure and phenomena in nucleon structure at low x.

Hadron Physics at RHIC49 July 6 th NLO QCD Analysis vs High p T Hadron Production in DIS DIS A 1 + A LL (π 0 ) DIS A 1 DIS A 1 + A LL (π 0 ) + neg ΔG initial High p T hadron production provides additional constraints to fit for 0.07 < x < 0.3, high p T data consistent with the three fit results for ΔG/G

Hadron Physics at RHIC50 July 6 th D. Boer and W. Vogelsang, Phys.Rev. D 69 (2004) Back-to-back di-Jets: Access to Gluon Sivers Function Current measurements should be sensitive at the level of predictions Measurements near mid-rapidity with STAR – search for spin-dependent deviation from back-to-back alignment > 7 GeV trigger jet > 4 GeV away side jet PHENIX: measurement of back-to-back di-hadrons.

Hadron Physics at RHIC51 July 6 th IFF Jet Proton Structure Hard Scattering Process Interference Fragmentation Jian Tang, Thesis MIT, June 1999 R. Jaffe, X.Jin, J. Tang Phys. Rev. D57 (1999)5920 X. Ji, Phys. Rev. D49 (1994)114 J. Collins, S. Heppelmann, G. Ladinsky, Nucl.Phys. B420 (1994)565 e+e- spin dep. FF extract pQCD PDFs Best Approach to Transversity at RHIC ?!

Hadron Physics at RHIC52 July 6 th 200 GeV 500 GeV Transverse Single Spin Asymmetry (Tang, Thesis, MIT) Maximum Asymmetry

Hadron Physics at RHIC53 July 6 th Example: 32 Rates for Asymmetries in Interference Fragmentation in PHENIX for 32 pb-1 1% 2% IFF from Belle A T from STAR+PHENIX

Hadron Physics at RHIC54 July 6 th Collins (and Interference) Fragmentation Function Measurement in e+e- at Belle       2-hadron inclusive transverse momentum dependent cross section:  e + e - CMS frame: e-e- e+e+ R. Seidl, spin: Th 17:30

Hadron Physics at RHIC55 July 6 th Collins Asymmetries for π + π - Pairs Experimental method to remove acceptance effects and asymmetries from QCD radiative processes. First direct measurement of the Collins function. First QCD analysis (Anselmino et al.) for Hermes and Belle data show good agreement between Belle FF and Hermes See this weeks PRL for details.. z1z1 z2z2

Hadron Physics at RHIC56 July 6 th LO-QCD Analysis of HERMES and Belle Results (Efremov, Goeke, Schweitzer, hep-ph/ ) BELLE PRELIMINARY HERMES PRELIMINARY Combined fit to Hermes asymmetries (Transversity x Collins-FF) and Belle asymmetries (Collins-FF 2 )  Excellent agreement!