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PHENIX G: Results and Prospect

PHENIX G: Results and Prospect. A.Bazilevsky BNL For the PHENIX Collaboration RHIC Spin: Next Decade Berkley, Nov 20-22, 2009. Daniel de Florian Rodolfo Sassot Marco Stratmann Werner Vogelsang. G: Global Fit. Phys. Rev. Lett . 101, 072001(2008)

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PHENIX G: Results and Prospect

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  1. PHENIX G: Results and Prospect A.Bazilevsky BNL For the PHENIX Collaboration RHIC Spin: Next Decade Berkley, Nov 20-22, 2009

  2. Daniel de Florian Rodolfo Sassot Marco Stratmann Werner Vogelsang G: Global Fit • Phys. Rev. Lett. 101, 072001(2008) • First truly global analysis of all available polarized data including RHIC results • Uncertainty estimation: • 2=1 (optimistic) • 2/2=2% (conservative) 2/2=2% Improved a lot after RHIC data have been included

  3. G: PHENIX Contribution 0 at s=200 GeV, ||<0.35 PRL 103, 012003 (2009) 0 at s=62 GeV , ||<0.35 PRD 79, 012003 (2009) Run 5+6 Run 6 Twice larger data sample collected in Run-2009 Data analysis ongoing

  4. G: PHENIX Contribution (not yet included in global fit) ± • Preferred fragmentation u+ and d-; • u>0 and d<0 different qg contributions for +, 0, -  access sign of G    • Analysis similar to 0 • Different flavor structure • Independent probe of G

  5. G: PHENIX Contribution (not yet included in global fit) ~80% Direct Photon • Quark gluon scattering dominates • Direct sensitivity to size and sign of G • Need more P2L Heavy Flavor • Production dominated by gluon gluon fusion • Measured via e+e-, +-, e, eX, X • Need more P2L

  6. G: PHENIX Contribution 0 at s=200 GeV  pT=2-12 GeV/c  xg=0.02-0.3 • Need to • Extend x-range • Constrain x

  7. G: Path Forward • Improve precision of current measurements • Extend x-range • Change s • Move to forward rapidities • Constrain kinematics (xg) • More exclusive channels

  8. Incl. 0 s=200 GeV ~0 Based on real efficiencies and yields from PHENIX data (Run6)

  9. Incl. 0 s=500 GeV ~0 Based on real efficiencies and yields from PHENIX data (Run9) Adds the lowest xT (xg) point – no competition for other points

  10. Incl. 0 s=62 GeV ~0 Based on real efficiencies and yields from PHENIX data (Run6) Considerably better sensitivity at higher xT (xg) compared to s=200 GeV

  11. s=62 – 500 GeV pT=2-2.5 GeV/c s: 200 GeV 500 GeV: xg (peak): 0.03  0.01 s: 200 GeV  62 GeV: xg (peak): 0.15  0.25 s=62 GeV also provides essentially better sensitivity for xg>0.08

  12. Forward Calorimetry • Muon Piston Calorimeter (MPC): PbWO4 • 3.1 < || < 3.7 • 2 azimuth • Fully available from 2008 • FOCAL: Tungsten absorber with silicon pad readout • 1<  <3 • 2 azimuth • 24 X0 deep • Available by 2013 (?)

  13. GS-C DSSV GS-C MPC: 0 at s=500 GeV • 3.1 < || < 3.7 25/pb, P=0.5 Phythia PYTHIA Lower-x parton Log10(x) Very good sensitivity to G at lower x (<0.01) even in limited data sample Asymmetries are low  need of spin flipper to reduce syst. uncertainties

  14. FOCAL: direct  at s=500 GeV Reconstructed ALL, PISA ALL 300 pb-1 @ 500 GeV 70% Pol Pythia 6.1 g q jet g q GS-A GS-B GS-C • PISA • Isolation Cut, Photon ID Cuts • No Background pT (GeV) Even direct photons may give reasonable sensitivity at lower x … but only with full luminosity and high beam polarization

  15. Silicon Vertex tracker (VTX & FVTX) Available in 2011/12 VTX barrel |h|<1.2 Q = c or b Q g g q g jet Q g q FOCAL: pT and photon VTX: jet Rejects hadronic background c/b separated measurements FVTX endcaps 1.2<|h|<2.7 mini strips May be luminosity (and polarization) hungry

  16. Summary • PHENIX 0 (along with STAR incl. jet) ALL data from Run-2005/6 at s=200 GeVhave made major contribution to G constraint in the xg range 0.02-0.3 • Collected Run-2009 data sample at s=200 GeV is about twice larger than Run-2006; analysis is ongoing • Lower s (e.g. 62 GeV) will considerably improve G constraint for xg>0.1 • Higher s (e.g. 500 GeV) + forward rapidity measurements give good sensitivity for xg<0.01 • low asymmetries  need of spin flipper • Many other channels (, ,,,e), each of them having smaller sensitivities to G than 0, altogether will give constraint similar to 0  should be included in global fit

  17. Backup

  18. Higher x parton Lower x parton

  19. Center of mass energy Center of mass energy Integrated Luminosity Integrated Luminosity ALL distribution as function of xg ALL distribution as function of pT PYTHIA Simulation Dg = g Simulation charm bottom Simulation GRSV_std L = 300 pb -1 L = 300 pb -1 P = 0.7 Dg = -g P = 0.7 200mm < DCA pT (GeV/c) include backgrounds xg no backgrounds ALL with VTX Heavy flavor measurement Gamma - jet correlation

  20. 1.5 2 5 Heavy Flavor Q = c or b Q g g Q

  21. From soft to hard PRD76, 051106 (2007) • Exponent (e-pT) describes our pion cross section data perfectly well at pT<1 GeV/c (dominated by soft physics): • =5.560.02 (GeV/c)-1 • 2/NDF=6.2/3 • Assume that exponent describes soft physics contribution also at higher pTs  soft physics contribution at pT>2 GeV/c is <10% exponential fit pT>2 GeV/c – hard scale?

  22. From soft to hard PRD76, 051106 (2007) xT scaling: Running (Q2) Evolution of PDF and FF Higher order effects Etc.  n=n(xT,Ös) 10-2 10-1 xT • Soft region: n(xT) increase with xT • If ~exp(-pT) • Hard region: n(xT) decrease with xT • Stronger scale breaking at lower pT 2 GeV/c at Ös=62 GeV pT~2 GeV/c – transition from soft to hard scale?

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