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Recent Spin Physics Results from

Recent Spin Physics Results from. University of Massachusetts Amherst. Christine Aidala. DNP Spin Workshop. October 25, 2006. Absolute Polarimeter (H jet). Helical Partial Snake. Strong Snake. RHIC as a Polarized p+p Collider. RHIC pC Polarimeters. Siberian Snakes. B RAHMS & PP2PP.

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Recent Spin Physics Results from

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  1. Recent Spin Physics Results from University of Massachusetts Amherst Christine Aidala DNP Spin Workshop October 25, 2006

  2. Absolute Polarimeter (H jet) Helical Partial Snake Strong Snake RHIC as a Polarized p+p Collider RHIC pC Polarimeters Siberian Snakes BRAHMS & PP2PP PHOBOS Siberian Snakes Spin Flipper PHENIX STAR Spin Rotators Various equipment to maintain and measure beam polarization through acceleration and storage Partial Snake Polarized Source LINAC AGS BOOSTER 200 MeV Polarimeter Rf Dipole AGS Internal Polarimeter AGS pC Polarimeter C. Aidala, DNP Spin Workshop, October 25, 2006

  3. Flavor separation of the quark and anti-quark sea Dq and Dq Heavy Flavors Prompt Photon Proton Spin Structure at PHENIX First moment of the spin-dependent gluon distribution DG Transversity and Sivers distributions Production C. Aidala, DNP Spin Workshop, October 25, 2006

  4. The PHENIX Detector for Spin Physics • g/p0/h detection • Electromagnetic Calorimeter • p+/p- • Drift Chamber • Ring Imaging Cherenkov Detector or TOF • J/y • Muon ID/Muon Tracker (m+m-) • EMCal (e+e-) • Relative Luminosity • Beam-Beam Counter (BBC) • Zero-Degree Calorimeter (ZDC) • Local Polarimetry -ZDC C. Aidala, DNP Spin Workshop, October 25, 2006

  5. PHENIX Polarized-Proton Runs:Longitudinal Polarization ** initial estimate C. Aidala, DNP Spin Workshop, October 25, 2006

  6. ALL Measurements N: # pions ++ same helicity +- opposite helicity R: luminosity++/luminosity+- • Procedure • Count N and luminosityfor ++ and +- configurations (sum over all crossings) and calculate ALL for each fill • Average ALL over fills; use c2/NDF to control fit quality • Perform checks, e.g. parity-violating AL consistency with zero C. Aidala, DNP Spin Workshop, October 25, 2006

  7. p0 Dg2 DgDq Dq2 0Cross Section at Ös=200 GeV NLO pQCD calculations are consistent with 200-GeV cross-section measurements. p0 Fraction pions produced h~0 C. Aidala, DNP Spin Workshop, October 25, 2006

  8. ALL of 0 at Ös=200 GeV C. Aidala, DNP Spin Workshop, October 25, 2006 Lower pT Run-6 points will come with full data reconstruction

  9. ALL of 0 at Ös=200 GeV • Run-6 data set from 2.0-2.7 times improvement on statistical uncertainties from Run-5. • Variation due to trigger turn-on GRSV: M. Gluck, E. Reya, M. Stratmann, and W. Vogelsang, Phys. Rev. D 63 (2001) 094005. • Theoretical uncertainties are not taken into account (for now). • Maximal gluon scenarios ruled out. • Expect clearer statement when lower-pT data from Run-6 is available Confidence Levels C. Aidala, DNP Spin Workshop, October 25, 2006

  10. Converting to xT, we can see the significance of the s=62.4 GeV data set compared to the Run-5 200-GeV preliminary data. p0 ALL at s=62.4 GeV • Measuring p0 ALL at s=62.4 GeV allows us to test a higher xT range. • dALL|R = 2.8x10-3. • p0 unpolarized cross section at s=62.4 GeV being analyzed. • Not yet clear how well NLO pQCD describes our data. • Need cross section to determine validity of comparison with expected ALL theory curves. Stay tuned! Theory curves by W. Vogelsang C. Aidala, DNP Spin Workshop, October 25, 2006

  11. p+, p - ALL and Dg • At transverse momentum > ~5 GeV/c, pions are dominantly produced via qg scattering • The tendency of p+ to fragment from an up quark and p- from a down quark and the fact that Du and Dd have opposite signs make ALL of p+ and p- differ measurably • This difference can allow us to determine the sign of Dg C. Aidala, DNP Spin Workshop, October 25, 2006

  12. Hard Scattering Process p+, p- Fraction of pion production Dg2 DgDq Dq2 ALL of ±at Ös=200 GeV • Proof-of-principle measurement from Run-5 • Charged pions begin firing the RICH at pT~4.7 GeV, which is used for particle ID. • Expect factor ~2.5 improvement for Run-6 uncertainties C. Aidala, DNP Spin Workshop, October 25, 2006

  13. h Dg2 DgDq Dq2 ALL of h at Ös=200 GeV h fragmentation function not yet available—needed for theoretical predictions! h C. Aidala, DNP Spin Workshop, October 25, 2006

  14. g DgDq DqDq Run-3 hep-ex/0609031 Prompt g Production at Ös=200GeV • Gluon Compton scattering dominates • At LO no fragmentation function • Small contribution from annihilation C. Aidala, DNP Spin Workshop, October 25, 2006

  15. Run-5 Eg R Prompt gat Ös=200 GeV (Run-5) Isolation cut to reduce background signal isolated p0 photon First step toward ALLg C. Aidala, DNP Spin Workshop, October 25, 2006

  16. ALL of J/y at Ös=200 GeV J/y C. Aidala, DNP Spin Workshop, October 25, 2006

  17. Understanding Transverse Spin Measurements in Hadronic Collisions • Theoretical interpretation of longitudinally polarized measurements at RHIC relies on various previous results from simpler systems • Fragmentation functions from e+e- experiments • Du, Dd from deep-inelastic scattering experiments • Relevant quantities for transverse spin calculations only starting to be measured now • E.g. Collins FF from BELLE (2005) • Intrinsic transverse momentum (kT) of the partons within the proton also essential in transverse spin calculations • Factorization theorem in pQCD including kT not yet proved! • Twist-three effects also seem important Lots of work still to be done, experimentally and theoretically! PHENIX is trying to do its part . . . C. Aidala, DNP Spin Workshop, October 25, 2006

  18. PHENIX Polarized-Proton Runs: Transverse Polarization ** initial estimate C. Aidala, DNP Spin Workshop, October 25, 2006

  19. PT MPC CENTRAL MUON BBC Kinematic Coverage @ 200GeV ZDC 0 1 2 3 4 5 6 Pseudorapidity PHENIX AN Measurements Mid-rapidity π0/h± • Run-2 (published), Run-5 (preliminary) • J/y • Forward neutrons • Forward p0 now possible with Muon Piston Calorimeter • Kinematic region where large asymmetries have been observed by STAR and BRAHMS! C. Aidala, DNP Spin Workshop, October 25, 2006

  20. AN of Mid-rapidity p0 and h±at Ös=200 GeV AN p0 PRL 95, 202001 (2005) AN h+/h- Run-5 Run-2 |h| < 0.35 hep-ex/0507073 |h| < 0.35 pT (GeV/c) pT (GeV/c) • AN is zero within 1% contrast with forward pions • Constrains Sivers distribution function for gluons (Anselmino et al., hep-ph/0608211) C. Aidala, DNP Spin Workshop, October 25, 2006

  21. charged particles neutron Run-5 Forward Neutrons at Ös=200 GeV Large asymmetry for xF>0 atÖs=200 GeV, no xF dependence observed. C. Aidala, DNP Spin Workshop, October 25, 2006

  22. AN of J/yat Ös=200 GeV • Sensitive to gluon Sivers function • Open charm theory prediction available from Anselmino et al. • How does J/y production affect prediction?? Waiting for theoretical calculation. C. Aidala, DNP Spin Workshop, October 25, 2006

  23. Run-5 Attempting to Probe kT from Orbital Motion kT larger kT smaller • Spin-correlated transverse momentum (orbital angular momentum) may contribute to jet kT. (Meng Ta-chung et al., Phys. Rev. D40, 1989) • Possible helicity dependence • Would depend on (unmeasured) impact parameter, but may observe net effect after averaging over impact parameter Same helicity Opposite helicity Di-hadron kT asymmetry C. Aidala, DNP Spin Workshop, October 25, 2006

  24. p0 AN xF<0 p0 AN xF>0 62.4 GeV f f Muon Piston Calorimeter (MPC) • PbWO4 calorimeter • 3.1 < |h| < 3.7 • Region of large observed asymmetries • South arm installed for Run-6 commissioning • Expect 200-GeV longitudinal and 62.4-GeV longitudinal & transverse results • Non-zero raw p0 transverse asymmetry already observed in 62.4-GeV data for xF > 0 • North arm just installed and ready for Run-7! C. Aidala, DNP Spin Workshop, October 25, 2006

  25. RHIC Data and Global Fits • Global fits of measurements sensitive to different processes and different kinematics essential to place tight constraints on nucleon pdf’s • DIS results will be combined with RHIC measurements of various probes • Pions, jets, heavy flavor, prompt photons, gamma-jet and jet-jet correlations, . . . • Two global fit papers already published including PHENIX p0 ALL data • M. Hirai et al., Phys. Rev. D74, 014015 (2006) • Navarro and Sassot, Phys. Rev. D74, 011502 (2006) C. Aidala, DNP Spin Workshop, October 25, 2006

  26. Summary and Prospects • The 2005 and 2006 RHIC runs have provided a wealth of additional data for spin physics, both longitudinal and transverse • Look for updated and additional results from PHENIX over the next months! • Moving into new era where RHIC will make decisive contributions to knowledge of polarized gluon distribution and more Many more years of exciting data and results to look forward to! C. Aidala, DNP Spin Workshop, October 25, 2006

  27. Extra Slides C. Aidala, DNP Spin Workshop, October 25, 2006

  28. pQCD Scale Dependence at RHIC p0 data vs pQCD with different factorization scales: Theoretical uncertainty of pQCD calculations in channels relevant for gluon polarization measurements: HERMES (hadron pairs) 2μ (factorization scale) COMPASS (hadron pairs) μ μ/2 RHIC (direct photon) PHENIX (direct photon) PHENIX (inclusive hadrons) Statistical errors only CDF (direct photon) CDF direct photon C. Aidala, DNP Spin Workshop, October 25, 2006

  29. Run03 -charged dn/d anti-aligned aligned 2 0  h Jet Asymmetry Due to Sivers Boer and Vogelsang, Phys.Rev.D69:094025,2004, hep-ph/0312320 • Non-zero Sivers function implies spin-dependence in kT distributions of partons within proton • Would lead to an asymmetry in Df of back-to-back jets • Trigger doesn’t have to be a jet or leading particle, but does have to be a good jet proxy • Studies being done for high-pT photon + away-side charged hadron (Schematic) C. Aidala, DNP Spin Workshop, October 25, 2006

  30. AN Reduction: Di-Hadron vs. Di-Jets AN away side parton di-hadron di-jet up down unpolarized • No full jet reconstruction  use di-hadron correlations to measure jet . Smears out di-hadron AN relative to di-jet AN, with smearing function g (assumed here to be Gaussian, with jT=0.35). Broadens and lowers the asymmetry, but still measurable C. Aidala, DNP Spin Workshop, October 25, 2006

  31. The PHENIX Detector • Philosophy: • High rate capability & granularity • Good mass resolution and particle ID • Sacrifice acceptance • 2 central spectrometers • - Track charged particles and detect electromagnetic processes • 2 forward spectrometers • - Identify and track muons • 2 global detectors • - Determine when there’s a collision C. Aidala, DNP Spin Workshop, October 25, 2006

  32. Total Raw Data Volumes • WAN data transfer and p+p data production at CC-J in RIKEN, Wako Japan • 60 MB/s sustained rate using Grid technology • 570 TB transferred in Runs 5 & 6 C. Aidala, DNP Spin Workshop, October 25, 2006

  33. ALL of ±at Ös=200 GeV C. Aidala, DNP Spin Workshop, October 25, 2006

  34. xT xT Scaling • xT scaling—can parametrize cross sections for particle production in hadronic collisions by: • Lower energy has higher yield at fixed xT We can probe higher xT with better statistics even with a short run at 62.4 GeV!! (compared to 200 GeV) C. Aidala, DNP Spin Workshop, October 25, 2006

  35. Run-5 ALL of Jet-like Clusters at Ös=200 GeV g • “Jet” detection: tag one high energy photon and sum energy of nearby photons and charged particles • Definition of pT cone: sum of pT measured by EMCal and tracker with R = (||2+||2) • Real pT of jet is evaluated by tuned PYTHIA C. Aidala, DNP Spin Workshop, October 25, 2006

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