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Kenneth N. Barish for the PHENIX Collaboration 28 th Winter Workshop on Nuclear Dynamics

sPHENIX Spin and Forward Physics. Kenneth N. Barish for the PHENIX Collaboration 28 th Winter Workshop on Nuclear Dynamics Dorado del Mar, Puerto Rico, April 2012. Forward Detector at sPHENIX. Primarily motivations p+ p : Forward transverse asymmetries

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Kenneth N. Barish for the PHENIX Collaboration 28 th Winter Workshop on Nuclear Dynamics

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  1. sPHENIX Spin and Forward Physics Kenneth N. Barish for the PHENIX Collaboration 28th Winter Workshop on Nuclear Dynamics Dorado del Mar, Puerto Rico, April 2012

  2. Forward Detector at sPHENIX • Primarily motivations • p+p: Forward transverse asymmetries • Separation of Sivers and Collins. • Factorization and universality of TMDs. • d+A: Cold Nuclear Matter • Calibration of quarkonium: J/y and ¡ families • Initial state of heavy ion collisions (connections to CGC/TMDs?) • A+A: • 3D “image” of medium • System expansion via photons

  3. The Proton Spin Structure • Polarization experiments • Helicity • Valence quarks • Sea quarks • Gluons momentum DSSV arXiv:0904.3821

  4. The Proton Spin Structure (p+p) • Polarization experiments • Helicity • Valence quarks • Sea quarks • Gluons • Transversity momentum momentum What is the connection to orbital angular momentum?

  5. Transverse Spin Asymmetries

  6. Transverse Spin Asymmetries • In (collinear) pQCD AN should scale like Asymmetries were expected to be very small.

  7. Transverse Spin Asymmetry Sources X. Ji, J.-W. Qiu, W. Vogelsang, F. Yuan, PRL 97, 082002 (2006) (III) Higher-twist effectsTwist-3 quark-gluon/gluon-gluon correlatorsExpectation: at large pT, AN ~ 1/pT So far, fall-off with pT has not been observed. (II) Sivers quark-distribution Correlation between proton-spin and intrinsic transverse quark momentum Graphic from Zhongbo Kang (I) Transversity quark distributionsand Collins fragmentation functionCorrelation between proton & quark spin + spin dependant fragmentation function Sivers distribution • Access to non-collinear PDFs • Needs orbital angular momentum of the quarks Quark transverse spin distribution Collins FF J. C. Collins, Nucl. Phys. B396, 161 (1993) D. Sivers, Phys. Rev. D 41, 83 (1990)

  8. Factorization & Universality • Collinear factorization for hadron-hadron scattering is well established and universality of the parton distributions are justified. • Less experimental data for polarized case, but the data is supportive and most theoretical foundations are common. • Foundation for DG and Dq programs. • Going beyond the twist-2 collinearly factorized picture is essential to explore QCD dynamics and fully understand the spin structure of the nucleon • Exploring the validity of factorization and universality of transverse momentum dependent (TMD) parton distributions factorization is key.

  9. Measurements Initial state interaction Sivers effect Hard Scattering Transversity Twist-3 Final state interaction Collins effect Transverse Asymmetries • Inclusive AN (central/forward) • Hadron Correlations (back-to-back) • Interference Fragmentation Functions • Jet correlations/structure • Drell-Yan Upgrades Upgrade plans • Separation of Sivers & Collins and test TMD parton distribution factorization and universality

  10. Global AN Analysis • A. Prokudin, Z.-B. Kang • arXiv:1201.5427 [hep-ph] • Input • HERMES • COMPASS • STAR 0 • Functional form similar to DSSV u quark Sivers d quark Sivers PP SIDIS • Need to map out Drell-Yan Sivers over a wide kinematic range

  11. Polarized Drell-Yan Production Estimated DY AN No fragmentation Direct correlation of intrinsic transverse quark properties and proton spin Solid factorization Fundamental QCD test Proposed Acceptance Current Acceptance Z. Kang and J. Qiu. Phys. Rev., D81:054020, 2010

  12. Drell-Yan Feasibility • Fast Monte-Carlostudies with effective detector smearing • QCD background decreases with increasing rapidity • Drell-Yan reduced signal

  13. What is Needed for DY Measurements? • Measure DY Sivers via p+pe+e— above the J/y but below the ¡ at √s=500 GeV • Asymmetry expected to peak at y~3 • Cover 2<h<4 • Charge sign determination • Work ongoing to understand how to shape field in large h region • e/p separation • Hadroniccalorimetry, preshower

  14. Jet Correlations / Structure Initial State (Sivers) • Jets with identified hadrons(measure AN for jets) • Do jets from certain quarks prefer to go left or right? Final State (Collins) • Left-right asymmetry of identified particle inside a jet • Do certain hadrons fragment from certain quarks to the left or right of the jet axis? Goal: Separate the initial state effects (Sivers) from final state effects (Collins). Then compare with other measurements (such as Drell-Yan Sivers). This will provide a stringent test of TMD PDFs factorization and universality.

  15. Jet Asymmetry (Sivers) Initial State (Sivers) • Jets with identified hadrons(measure AN for jets) • Do jets from certain quarks prefer to go left or right? √S = 200 GeV y=3.3 jets • Zhong Bo Kang et al. arXiv:1103.1591 • Measurements of jet asymmetry in forward direction sensitive to quark-gluon correlation function. twist 3 Fit of SIDIS SIDIS old

  16. Hadrons in Jets (Collins) Final State (Collins) • Left-right asymmetry of identified particle inside a jet • Do certain hadrons fragment from certain quarks to the left or right of the jet axis? • F. Yuan, PLB 666 (2008) 44-47 • Direct Collins measurement of fragmentation • Expect large asymmetries in forward direction jet ®h+X

  17. What is needed for Jet measurements? • Good Jet reconstruction to be able to measure Sivers cleanly • Electromagnetic and hadroniccalorimetry • Particle ID to measure Collins effect • Collins effect different for different hadrons RICH • B Field and tracker to determine charge sign of hadrons Sivers Collins

  18. Cold Nuclear Matter (d+Au) • The Physics • Calibration of quarkonium: J/y and ¡ families • Initial state of heavy ion collisions • connection to CGC • connection to spin physics: TMD PDFs • RHIC’s uniqueness • Ö s dependence • Possibility of different species • Low Q2 • What drives the design • Large data samples • 1>h>4 • Detector sensitive to e, g, charged hadrons, jets Direct photon Drell- Yan Open Heavy Flavor

  19. Calibration of quarkonium d+A • Each measurement is sensitive to various effects • Using a redundant set of measurements will allow the isolation of the necessary components

  20. Color Glass Condensate (CGC) Gluons Saturation xG(x) x CGC • High density limit  low-x forward rapidity • Calculable regime of gluons at high density but weak coupling • Nuclear Amplification xGA~A1/3xGp • Gluon saturation: characterized by Qsat • Predictions • Suppression • Low-x or forward η • More central • “Suppression” of away side jet move boundary by changing Centrality to Map out QS 10-4 fsPHENIX Y=1-4 10-3 Prediction; Suppression : Low-x or forward η More central x 10-2 Central Arms Y~0 10-1 QS ~1-2GeV @RHIC 1 100 10 1 20 Q (GeV) QCD~220 MeV Low –x is key

  21. Connection with TMDs? • Problem: TMD factorization violated for dijet production in hadron+hadron collisions • Solution: Get back effective TMD factorization in case of small x partons at high density (“CGC regime”) – probed by quark, or photon • Problem: TMD parton distributions not universal • Solution: they can be constructed for building blocks which ARE universal. • e.g. Gluon PDF G(1)(x,q^), G(2)(x, q^) • quantities derived via CGC and via TMD identical • Equivalence between TMD and CGC approach in “CGC” regime • Connections to TMD’s in spin? xG(2)(x,q^) xpfq(xp) Domingues, Marquet, Xiao, Yuan arXiv:1101.07152v2, PRL 106, 022301 • Measure : photon-jet & dijets at low-x in d+Au

  22. Heavy-ions (Au+Au) • 3D “image” of medium • At mid-rapidity only see only the evolution/final state of the “slice” of the fluid which is initially at rest longitudinally. • Make flow measurements in forward direction. • Forward photon measurements • Information on system expansion / early evolution. • Access to high baryon density region. Talk by P. Stankus • Bjorken: boost-invariant expansion • Landau: complete initial T. Renk, PRC71, 064905(2005)

  23. PHENIX Design

  24. sPHENIXConceptual Design Tracker EMcal Hcal 2T Magnet RICH EMCal HCal MuID *Not to scale

  25. Mid Rapidity Region • Ali Hanks talk Tuesday • Full 2p coverage • Electromagnetic and Hadroniccalorimetry • 2T Solenoidal Field • VTX detector for central tracker • Also allow heavy quark jets • Primary (initial) focus of jet and di-jet measurements in HI • Designed to include possible upgrade path: additional tracking, EID, ePHENIX • Will take full advantage of RHIC’s flexibility: d+A, Cu+Au, U+U, etc.

  26. Forward Region • Rely on central magnet field • Studying other field/magnet possibilities • EMCal based on restack of current PHENIX calorimetry • PbSc from central arm (5.52 cm2) • MPC forward arm (2.2 cm2) • For tracker considering GEM technology • Interest of HI in forward direction may influence choices based on expected multiplicity. PbSc restack MPC restack =12x12 towers 1 tower is 5.5cm2 = 2.2cm2

  27. Outlook • sPHENIX Forward will significantly extend physics capabilities • With new Forward Detector, will be able to understand large SSA, separating contributions from Sivers and Collins. • Forward Detector will also provide calibration for quarkonium measurements and probe CNM effects in d+A (connections with CGC and TMDs?) • Potential exists to explore 3D image of medium in Au+Au • Workshops planned. Multiple funding sources pursued. • Staged implementation approach • Drell-Yan/Quarkonia needs only EMCal, charged particle ID, and charge sign • Then add jet followed by identified hadron capabilities. • The sPHENIX forward would also be well matched with ePHENIX.

  28. Backups …

  29. Drell-Yan Feasibility

  30. Figure 6: Accessible partonicmomenta in p+p collisions at s=500 GeV for different detector acceptances (pseudo-rapidity). The horizontal axes represents the polarized proton. The plots are for intermediate virtual photon masses between J/ and ¡ (3.5 Gev/c < minv < 9.0 GeV/c), with increasing masses the distribution broadens towards larger x2.

  31. Towards eRHIC Forward Backward  EMCal Minimal configuration/requirements: • Backward: electrons, photons • Barrel: electron, photons, hadrons • Forward: hadrons • Roman Pots for forward protons R [cm] Magnet 70 PID Barrel cross section diagram 60 Immediate focus: Make sure sPHENIX concept of barrel consistent with upgrade plans for ePHENIX physics sPHENIXcentral arm proposal (CD0) to be submitted on Jul 1, 2012 Is EMCal resolutions good enough? Enough space for PID? Momentum range for PID Material budget limitation for tracking 10 p/A e- 0 Outer tracker Additional tracking as needed Inner Tracker

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