Kieran Boyle (RIKEN BNL Research Center)

1. Current Results and Future Prospects from Kieran Boyle (RIKEN BNL Research Center)

2. Topics • Longitudinal Spin • Current results • Future plans/ideas • W physics • Plans • A first look at Run9 data • Transverse Spin • Current Results • Future plans

3. RHIC and PHENIX A few standard slides

4. RHIC BRAHMS & PP2PP (p) PHENIX (p) STAR (p) RHIC CNI (pC) Polarimeters Absolute Polarimeter (H jet) Siberian Snakes Spin Rotators Partial Siberian Snake LINAC BOOSTER Pol. Proton Source AGS Longitudinal AGS Internal Polarimeter 200 MeV Polarimeter Transverse Rf Dipoles In progress

5. BBC PHENIX Detector p0, h, g detection • Electromagnetic Calorimeter (PbSc/PbGl): • High pT photon trigger to collect trigger to collect p0's, h’s, g’s • Acceptance: |h|<0.35, f = 2 x p/2 • High granularity (~10*10mrad2) p+/ p- • Drift Chamber (DC) for Charged Tracks • Ring Imaging Cherenkov Detector (RICH) • High pT charged pions (pT>4.7 GeV). W± from e± • EMCal: triggering and energy determination • DC: Sign determination W± from ± • Muon Identification (MuID) • Tracking (MuTR) • Triggering (RPC and MuTrig Upgrades) Relative Luminosity and Local polarimetry • Beam Beam Counter (BBC) • Acceptance: 3.0< h<3.9 • Zero Degree Calorimeter (ZDC) • Acceptance: ±2 mrad EMCal ZDC ZDC

6. Hard Scattering Process p0 DG2 DGDq Dq2 Constraining G Current Longitudinal Spin Program with DS ~25%, DG not as well constrained, L?

7. Why ALL? • If Df = Dq, then we have this from pDIS • So roughly, we have From e+e- (& SIDIS,pp) From ep (&pp) (HERA mostly) pQCD NLO +- = + = ++ +

8. pQCD works Direct g @ 200 GeV p0 @ 200 GeV arXiv:0704.3599 [hep-ex]

9. ALL Results Large number of independent probes Accepted in PRL: arXiv:0810.0694

10. Focus on 0 • Why 0? • Nothing special about 0 physically • Similar to other single hadron or jet measurements • Pions are abundantly produced in p+p collisions • 0 ~99% of the time • PHENIX triggering on high pT photons ensures large sample • Fragmentation Function is also reasonably well known • Will get better with BELLE data • Marquee measurement in the age of low luminosities.

11. Constraining G • Vary G in GRSV fit, and then generate ALL. • Calculate 2 for each expectation curve, and plot profile arXiv:0810.0694 Use combined Run5 and Run6 results

12. PRL 101, 072001(2008) First truly global analysis of polarized DIS, SIDIS and pp results PHENIX s = 200 and 62 GeV data used (PRELIMINARY 2006) RHIC data significantly constrain G in range 0.05<x<0.3 Experimental systematic uncertainties must be included taking into account correlations. Theoretical uncertainties must be considered. See recent paper. Recent Global Fit: DSSV

13. Systematic Uncertainty Impact Accepted in PRL: arXiv:0810.0694 • Consider impact of dominant uncertainties: • Polarization • Relative luminosity • Polarization has negligible impact on G constraint • Relative luminosity though small (4.6x10-4) is not neglible • G(syst) = 0.1

14. Parameterization Uncertainties Parameterization choice • Vary g’(x) =g(x) for best fit, and generate many ALL • Get 2 profile • At 2=9 (~3), we find consistent constraint: -0.7 < G[0.02,0.3] < 0.5  Our data are primarily sensitive to the size of G[0.02,0.3].

15. Scale Uncertainty Theoretical Scale Uncertainty: • 0 cross section is described by NLO pQCD within sizable uncertainty in theoretical scale  • How does this affect G constraint? • Vary scale in ALL calc.  0.1 uncertainty for positive constraint  Larger uncert. for negative constraint

16. R. Bennett’s Thesis Direct Photon G Constraint ~80% • Dominated by quark-gluon Compton scattering • Distinct process from other current RHIC probes • At Leading Order • Calculate most probable x(gluon) for given pT • Monte Carlo • Get A1p from DIS experimental result • PRD 60 (99) 072004 • Partonic asymmetries calculable in pQCD • Phys.Rept.59:95-297,1980

17. R. Bennett’s Thesis G/G from Direct Photon • Current data are ~10 pb-1, so very limited statistics • If we get expected luminosities and polarizations at 200 (and in future) 500 GeV, will offer significant constraint.

18. Future for PHENIX G Lower x, correlations and Higher Luminosity

19. Higher s allows access to lower x For W program, we need significant luminosity (~300 pb-1) For ALL, if polarization is >60%, this will allow for a very accurate measurement of G. We will of course repeat our measurements ALL expected to be small Systematic uncertainties will become significant at low pT, where lowest x is reached. present (0) x-range s = 200 GeV Extend to higher x at s = 62.4 GeV Extend to lower x at s = 500 GeV s=500 GeV

20. Expectation for 0 ALL • Limited at high pT due to merging of photons as opening angle decreases • Relative luminosity systematic uncertainty must be reduced. Full spin program

21. Particle Correlations • Due to limited acceptance, Jet-Jet measurement is extremely difficult in PHENIX. • Two particle correlations can be measured, though this introduces two fragmentation functions. • Also will look at photon-hadron correlations.

22. |h| < 0.35 Direct g PHENIX jet Jet Simulation |hjet| < 1.2 Silicon Vertex Detector (VTX) • Four layers (2 pixel, 2 stripixel) • Allow access to G through distinct processes • Heavy flavor via displaced vertices • Gamma-Jet (isolated trigger photon in EMCal, charged energy from VTX) Heavy flavor • DCA resolution ~50m • c/b separation by c Life time (ct) D0 : 125 mm B0 : 464 mm e DCA Gamma Jet • Large acceptance: ||<1, ~2 for  D p p B e

23. W-bosons at PHENIX Accessing the flavor dependent quark sea spin distributions l+

24. e+/- Two ways to get W • Central Rapidity: ||<0.35 • Measure electron in the central arms EMCal • Determine charge sign from tracking • Forward/Backward: 1.2<<2.4 • Measure muon in muon arms • W dominates muon signal above 20 GeV • For measurement, we require: • Ability to trigger on high momentum  • Hadron background reduction • Upgrading PHENIX for this purpose Muon pT spectra in the Muon Arms (2000 [1/pb], from PYTHIA5.7) μ ± W

25. W • Expectations based on 300 pb-1, 60% pol. • Different rapidities select different polarized quark and anti quark distributions Forward AL μ+ Forward AL μ- Backward AL μ+ Backward AL μ-

26. W Rapidity: 1.2 < h <2.2 (2.4) • <Muon Trigger Upgrade> • MuTr FEE Upgrade (MuTRG) • Install RPC (Resistive Plate Chamber) • Install additional Pb absorber • MuID • - only existing trigger • no momentum selectivity.. 26

27. We in Central Arms • Cross section of e+/- from W & π+/- in the PHENIX acceptance. • Expected asymmetry of W (assuming 70 % polarization, no background or detector resolution included) pions: NLO pQCD calculation from W. Vogelsang W: RHICBOS (Nadolsky, Yuan) pi+ pi+ e+ e- <Charged hadron rejection> EMCal intrinsic: 50-150 Shower profile: 2-4 Isolation cut: ~10 Total: 1000-6000

28. We Run 9 Energy v.s. Inclination of the track • Polarization ~35% • Luminosity ~10%  Measure cross section • alpha [rad.] ~ 0.1/ mom [GeV/c] • “energy / mom < 3” cut applied negative charge positive charge eta Energy dist. (Black: +, Red: -) Only analyzed part of data set pi0

29. Event Display of High energy events Found W candidates. Analysis is under way! 3. W detection @ PHENIX 29

30. Transverse Spin results

31. AN from p0, h+/- (<0.35) PHENIX transverse running in 2005 PHENIX transverse running at 2002 PRL 95, 202001 (2005) Analysis with high statistics 2006+2008 data in progress Smaller statistical uncertainties (more than factor of 7 improvement)Higher pT data points possible

32. Constrain gluon Sivers effect p0 AN from PHENIX 2002 data Anselmino et al, Phys. Rev. D 74, 094011 Upper bound for gluon Sivers function that is consistent with PHENIX results, assuming vanishing sea contribution

33. Forward p0 AN Forward asymmetries contain mixture of • Sivers • Transversity x Collins PHENIX 0 results available for s=62GeV Analysis of large 2008 s=200 GeV dataset – AN of 0 and – 5.2 pb-1, 46% Polarization – work in progress Process contribution to 0, =3.3, s=200 GeV PLB 603,173 (2004)

34. SSA from di-hadron production • SSA from Interference Fragmentation Function (IFF) • Measure di-hadron asymmetry with hadron pairs in central arm (0,h+) (0,h-), (h+,h-) • Transversity extraction will become possible with Interference Fragmentation Function measurement in progress at BELLE • Two different theoretical models gave different prediction of mass dependence • Sign change is not observed in HERMES/COMPASS results Jaffe, Jin and Tang, PRL 80 (1998) 1166 Bacchetta and Radici, Phys. Rev. D 74, 114007 (2006)

35. IFF: Definition of Vectors and Angles Bacchetta and Radici, PRD70, 094032 (2004)

36. SSA from di-hadron production No significant asymmetries seen at mid-rapidity. Added statistics from 2008 running

37. SSA from di-hadron production No significant asymmetries seen at mid-rapidity. Added statistics from 2008 running

38. Summary • PHENIX has measured ALL of numerous final state particles which can constrain G • While neutral pions have been used by DSSV, other measurements, while statistically limited individually, will make the result more robust. • Future G constraint will also include particle correlation. PHENIX is well prepared to measure photon-hadron correlations, and with the VTX, can look at photon jet. • PHENIX is on schedule for the W physics program, and are studying results from the recent engineering 500 GeV run. • PHENIX has a number of transverse spin measurements, from the recent long transverse runs, and will have more to come.

39. Backups

40. Measuring ALL • Helicity Dependent Particle Yields • p0, p+, p-, g, h, etc • (Local) Polarimetry • Relative Luminosity (R=L++/L+-) • ALL + - = Opposite helicity = + = + ++ = Same helicity

42. Fragmentation Functions • Cross sections in e+e- for 0, +, -, +, -,  • 60 fb-1 data below b resonances • 600 fb-1 data at b resonances • Can be used for high z data if statistics are an issue • Not an issue for above particles • Data will be systematically limited

43. R. Bennett’s Thesis Estimating Average x gluon