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A LL measurement in π ± production at RHIC p-p collider to constrain ΔG

A LL measurement in π ± production at RHIC p-p collider to constrain ΔG. SOOKHYUN LEE (Stony Brook University) On half of PHENIX Collaboration . Intro. Spin puzzle and pDIS experiment

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A LL measurement in π ± production at RHIC p-p collider to constrain ΔG

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  1. ALL measurement in π± productionat RHIC p-p collider to constrain ΔG SOOKHYUN LEE (Stony Brook University) On half of PHENIX Collaboration S.LEE SPIN 2010 at Germany

  2. Intro • Spin puzzle and pDIS experiment • Fully inclusive processes : Quark flavor summed (charge weighted) polarized pdfs, g1 ~ observable • Flavor decomposition needs combining different experimental channels ; nucleon and hyperonβdecays or semi inclusive DIS. • Puzzling results from European Muon Collaboration (EMC) in 1988 • Total quark contributions to proton polarization is only ~25% at Q2=10GeV2 • No direct coupling to gluons • No direct way of extracting gluon polarized pdf. ; ambiguous definition • Polarized PP experiment • Direct coupling of quarks to gluons • Allow to access gluon polarization • Double as well as single asymmetries as observables • Provides more opportunities to disentangle polarized pdfs S.LEE SPIN 2010 at Germany

  3. ALL for Single Inclusive π± Production • dσ : Definite helicity cross section • p(+) : Longitudinally polarized protons in the same direction as their movement. • p(-) : Longitudinally polarized protons in the opposite direction as their movement. PRD19,1483(1979) S.LEE SPIN 2010 at Germany

  4. Parton Model for Polarized Proton Collisions (for single inclusive hadron production) Helicityparton density Hard scattering Cross section Fragmentation function S.LEE SPIN 2010 at Germany

  5. (Un)Polarized Parton Distribution Functions Polarized PDF Δf a/A = fa(+)/A(+) – f a(+)/A(-) Numerator Integrate over x helicity sum rule (A+=0 gauge) Jaffe, Manohar; Ji; … Unpolarized PDF f a/A = fa(+)/A(+) + f a(+)/A(-) Denominator S.LEE SPIN 2010 at Germany

  6. Charged pions and ΔG Duπ+ >Duπ0 >Duπ- , Dgπ+=Dgπ+ For positive ΔG : Aπ+LL >Aπ0LL >Aπ-LL DSSV PRD80:034030(2009) S.LEE SPIN 2010 at Germany

  7. Other Relevant Measurements * * For central arm detectors at√s =200GeV jet ALL K. Nakano ’s talk π0 ALL A. Manion’s talk ηALL J.F. Ellinghaus’s talk h± ALL  C. Aidala’stalkγ ALL  P. Kline’s talk W AL K. Okada’s talk S.LEE SPIN 2010 at Germany

  8. Longitudinally Polarized p+p Runs at PHENIX In Run ending in 2011 and 2012, goal is to achieve 20 pb-1 and 35 pb-1repectively. S.LEE SPIN 2010 at Germany

  9. Absolute Polarimeter (H jet) RHIC pC Polarimeters Siberian Snakes BRAHMS RHIC PHENIX (p) STAR (p) Siberian Snakes Spin Rotators Solenoid Snake LINAC BOOSTER Pol. Proton Source AGS Warm Snake 200 MeV Polarimeter AC Dipole AGS pC CNI Polarimeter Cold Snake RHIC & ALL measurements • Every 106(time between bunch crossings)*8(crossings) ns, one of four possible spin patterns completes : Reduces systematic uncertainty Blue Yellow • Spin Rotators allow polarization to be changed from longitudinal to vertical outside interaction region: perform polarization measurements using elastic p-p collisions ( i = bunch x-ing ) S.LEE SPIN 2010 at Germany

  10. Finding Charged Pions At PHENIX • PHENIX Central Arm detector • |h| < 0.35, Df = 180 degrees • Drift chamber, Pad chamber • Charged particle tracking • Determine pt of charged tracks • Cherenkov detector(RICH) • Using data with threshold 1.4GeV • Pion threshold at pt ~ 4.7GeV/c • Electromagnetic Calorimeter(EMCal) • EMCal - RICH Trigger for high statistics for high pt particles S.LEE SPIN 2010 at Germany

  11. A peek into Analysis Charged pion yield / Luminosity (ERT-scaled-down BBC counts ) has to be constant if efficiencies are stable as it is proportional to a physical quantity cross section. Systematic check using Parity conservation: dσ++ + dσ- + - dσ+ - - dσ- - = 0 Charged pion yield / Luminosity (ERT-scaled-down BBC counts ) has to be constant if efficiencies are stable as it is proportional to a physical quantity cross section. Systematic check using Parity conservation: dσ++ + dσ- + - dσ+ - - dσ- - = 0 S.LEE SPIN 2010 at Germany

  12. Preliminary results for Run 9 ALLp+ from Run-09, compared to NLO prediction using DSSV polarized pdfs ALLp- from Run-09, compared to NLO prediction using DSSV polarized pdfs S.LEE SPIN 2010 at Germany

  13. Results from combined PHENIX data ALLp+ from Run-05, -06, -09 preliminary data, compared to NLO prediction using DSSV polarized pdfs ALLp- from combined Run-05, -06, -09 preliminary data, compared to NLO prediction using DSSV polarized pdfs S.LEE SPIN 2010 at Germany

  14. Comparison of asymmetries for three pion species from combined PHENIX data sets S.LEE SPIN 2010 at Germany

  15. Outlook • Include results in Global analysis • Further constrain ΔG on top of recent RHIC π0 results’ impact (K. Boyle’s talk) • Future outlook • Collectmore statistics • Higher twist (higher order in Λ/Q) effect? • Look at γ-jet, hadron-jet or combination thereof • Need larger geometrical acceptance and integrated luminosity • Study on viability of this analysis underway with silicon vertex detector( -1.0 <η< 1.0) in place in 2011. S.LEE SPIN 2010 at Germany

  16. Backup S.LEE SPIN 2010 at Germany

  17. Parity conserving strong interaction S.LEE SPIN 2010 at Germany

  18. Polarization of Proton Beam • All asymmetries need polarization as an input to account for imperfect polarization of proton beam. • ALL ~1/(PP) • AL ~ 1/P • Hydrogen jet polarimeter provides absolute polarization. • pCpolarimeter allows for abundant statistics; complementary with H-jet polarimeter. Transversely polarized pp elastic scattering S.LEE SPIN 2010 at Germany

  19. All 4 possible spin patterns • Left-Right : Blue and Yellow bunch patterns are swapped. • Top-Bottom : Even bunches are negate of odd bunches. S.LEE SPIN 2010 at Germany

  20. Relative beam shift correction • Take Φ and dα data from zero (magnetic) field run. • Extract relative beam position with respect to the center of DC arc for east and west arm separately. • Get correct α values that give in turn correct momentum pt. S.LEE SPIN 2010 at Germany

  21. RICH detector S.LEE SPIN 2010 at Germany

  22. PC3 and EMcal Matching calibration • Found non-zero offsets in official recalibrator matching parameters emc_sdphi, emc_sdz, pc3_dphi and pc3_dz • Fit them with double Gaussian function for different pt and charge bins. • No pt dependence correction needed since matching parameters saturate above pt>5GeV/c. S.LEE SPIN 2010 at Germany

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