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Transverse Spin Physics at RHIC

This workshop focuses on the transverse spin physics at RHIC, including the measurement of the Sivers function, extraction of transversity distributions, and the study of back-to-back correlations in jets.

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Transverse Spin Physics at RHIC

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  1. Transverse Spin Physics at RHIC International Workshop on Semi-Inclusive Reactions and 3D-Parton Distributions May 18-20, 2005 Jefferson Lab, Newport News, Virginia, USA M. Grosse Perdekamp (University of Illinois and RBRC)

  2. Transverse Spin Physics at RHIC • Motivation • Measurement of the Sivers function • Extract transversity distributions from QCD analysis: SIDIS + pp + e+e- • Polarized p-p at RHIC • Polarized collider + experiments • Does NLO pQCD provide stable framework for the extraction of polarized PDFs? • Transverse Spin Physics • AN  Sivers, transversity/Collins, sub-leading twist • back-to-back correlations in Jets  Sivers • AT (Collins, IFF)  Transversity/Collins • AT (Drell Yan)  Sivers • ATT (Drell Yan)  Transversity • Summary Transverse Spin Physics at RHIC

  3. Motivation: Global Transversity Analysis RBRC workshop September 2000 Factorization and Universality? Transversity Tensor Charge Does pQCD provide a stable frame work for a global transversity analysis? BLT sum rule and Lattice QCD Transverse Spin Physics at RHIC

  4. Collins FF (and IFF): e+e-  hadrons (see Akio Ogawa’s talk) e+e- CMS frame: j2-p e- Q j1 j2 j1 e+ 2-hadron inclusive transverse momentum dependent cross section: Transverse Spin Physics at RHIC

  5. Polarized p-p at RHIC 2005: complete instrumentation! RHIC pC Polarimeters Absolute Polarimeter (H jet) Siberian Snakes BRAHMS & PP2PP PHOBOS Siberian Snakes Spin Flipper PHENIX STAR Run 04 Spin Rotators Partial Snake Helical Partial Snake Strong Snake Pb~45% , 55 bunches Polarized Source Run 05 LINAC AGS BOOSTER 200 MeV Polarimeter <Pb> = 45% Rf Dipole Commision strong snake AGS Internal Polarimeter AGS pC Polarimeter Transverse Spin Physics at RHIC

  6. RHIC 2005: 200 GeV pp, ∫Ldt, May 17th PHENIX Goal 5.5 pb-1 live BBCLL1 (5/17/05) June 25, 2005 (3.56 pb-1 projected) 2.88 pb-1 live ZDCLL1 1.23 pb-1 live BBCLL1 27.7 B BBCLL1 events sampled Transverse Spin Physics at RHIC

  7. RHIC 2005: 200 GeV pp, FoM, May 17th PHENIX Goal 226 nb-1 June 25, 2005 (5/17/05) (190 nb-1 projected) 60.2 nb-1 Transverse Spin Physics at RHIC

  8. Goals for 2005:  (a) 1stlook at the Gluon Polarization (b) precision measurment of AN ALL in inclusive jet production (STAR) Jager, Stratmann, Vogelsang hep-ph/0404057 ALL(Jets) ∫Ldt=3pb-1 P=0.4 Input: ∆G(x)=G(x) GRSV: standard ∆G(x) ∆G(x)=0 ∆G(x)= -G(x) pT [GeV/c] ALL in inclusive π0 production (PHENIX) Vogelsang hep-ph/0405069 ALL(π0) ∫Ldt=3pb-1 P=0.4 Input: ∆G(x)=G(x) GRSV: standard ∆G(x) ∆G(x)= -G(x) ∆G(x)=0 pT [GeV/c] • GRSV standard ∆G(x) • Gluon distribution from NLO pQCD fit to DIS data on A1, Gluck Reya, Stratmann, Vogelsang Phys. Rev. D63:094005, 2001 Expected in run 05: ∫Ldt =5pb-1 P =0.5 All required instrumentation in STAR and PHENIX is in place! Transverse Spin Physics at RHIC

  9. Experiments with polarized protons at RHIC polarizationmeasurements STAR75% longitudinal, 25% transverse ALL (hadrons, jets, direct photons) AL (W-bosons) AN (hadrons, jets), AT (Drell Yan, Collins, IFF) ATT (Jets, Drell Yan) PHENIX75% longitudinal, 25% transverse BRAHMS100% transverseAN (identified charged hadrons) PHOBOS, pp2pp  no “active” spin program Transverse Spin Physics at RHIC

  10. Does pQCD provide a stable for the extraction of PDFs at NLO from RHIC data? PHENIX π0 cross section a |η|<0.35 Phys.Rev.Lett.91:241803,2003 STAR π0 cross section a 3.4<η<4.0 Phys.Rev.Lett.92:171801,2004 gluon fragmentation !? o Good agreement between NLO pQCD calculations and experiment  can use a NLO pQCD analysis to extract spin dependent quark and gluon distributions from RHIC data! Transverse Spin Physics at RHIC

  11. Direct Photons: NLO pQCD vs RHIC data • NLO-pQCD calculation • Private communication with W.Vogelsang • CTEQ6M PDF. • direct photon + fragmentation photon • Set Renormalization scale and factorization scale pT/2,pT,2pT Scale dependence of Cross sections in NLO pQCD calculations Transverse Spin Physics at RHIC

  12. E704: AN • Fermilab E-704 reported large • asymmetries AN in pion productions The observed asymmetries could result from Transversity x Spin-dep.fragmentation (Collins-Heppelmann effect), or Sivers effect or Higher-twist effects • Sterman and Qiu Initial State Twist 3 • Koike Final State Twist or a combination of the above E704 • 0 – E704, PLB261 (1991) 201. • π+/- - E704, PLB264 (1991) 462. left right PT=0.5~2 GeV/c Transverse Spin Physics at RHIC

  13. Transverse Spin Physics at RHIC, first Results: AN Run 02, ∫Ldt ~ 0.2pb-1, P~0.15 STAR AN(π0) at 3.4<η<4.0 Phys.Rev.Lett.92:171801,2004 PHENIX AN(π0) and AN(π0)at |η|<0.35 C. Aidala, DIS 2004, to be published o Experiments are ready for spin measurements at low luminosity  relative luminosity ~ 5x10-4  trigger  polarization analysis  data analysis o First spin results from RHIC  AN sizeable in forward XF  AN compatible with 0 at η~0 Transverse Spin Physics at RHIC

  14. STAR: AN for backward angles from 2003 data Run 3 preliminary backward angle data  no significant asymmetry (hep-ex/0502040) Transverse Spin Physics at RHIC

  15. BRAHMS: AN for charged pions AN for pions: AN= +0.05 +- 0.005 +- [0.015] pT vs XF AN= -0.08 +- 0.005 +- [0.02] in 0.17 < xF < 0.32 xF x 100 • o From the ongoing 2005 run the • statistical errors will be reduced • by a factor 6-7 • o New absolute RHIC polarimeter will • reduce the systematic error by a factor 4 • What can be learned from confronting model calculations with precision data on AN? xF x 100 Transverse Spin Physics at RHIC

  16. AN for Protons from BRAHMS BRAHMS preliminary e • Proton AN is compatible with 0 • AN will be available for pions, kaons and protons from run 2005 • What do we learn from comparing AN for different fragmentation functions? Transverse Spin Physics at RHIC

  17. Future: RHIC Spin Longitudinal vs Transverse Running L= 6x1030cm-2s-1 8x1031cm-2s-1 P= 0.45 0.5 0.7 …………………………………………. √s= ……………………….. 200 GeV ………………….........| 2004 2005 2006 2007 2008 2009 …. pp 5+0 5+10 5+11 0 5+9 156pb-1 Inclusive hadrons + Jets ~ 25% Transverse Physics Charm Physics direct photons Bottom physics W-physics ALL(hadrons, Jets) ALL(charm) AL(W) ALL(γ) Transverse Spin Physics at RHIC

  18. (A) Transverse Spin Physics Channels at RHIC for “Low” Luminosity STAR and PHENIX STAR, PHENIX and BRAHMS (I) (II) Boer and Vogelsang (hep-ph/0312320): azimuthal back to back correlation between hadrons in opposite hemisphere jets: STAR Phys. Rev. Lett. 92:171801, 2004 Clean channel for Sivers effect! Separation of intrinsic transverse quark spin (transversity) from trans- verse momentum effects (Sivers)? Transverse Spin Physics at RHIC

  19. Sensitivity Check for Back-to-Back Sivers Asymmetry (based on 2003 pp sample) Full di-jet Sivers Reduced by lower <P>, di-hadron smearing Run03 p+p gamma-charged, 0.35/pb • Given 0.35/pb of data, we should be able to get 1% statistical • significance in AN using gamma-charged measurements of jet dphi • Expected raw AN could be 3.5% • Could also be as low as 0.5%, or as large as 10% • x-dependence of Sivers? • Effects from P=0.5, jet angle not aligned with transverse polarization, • and fragmentation reduces raw AN to ~1.0% • Have not evaluated systematic errors yet (underlying event…) Transverse Spin Physics at RHIC

  20. (B) Transverse Spin Physics Channels at RHIC for “High” Luminosity STAR and PHENIX STAR and PHENIX W. Vogelsang and M. Stratmann, RBRC Wrkshp on Transversity (2000) J.C. Collins, Nucl. Phys. B396, 161(1993) J. Collins, S. Heppelmann, G. Ladinsky, Nucl.Phys. B420 (1994)565 R. Jaffe, X.Jin, J. Tang Phys. Rev. D57 (1999)5920 Statistical sensitivity for AT with 32pb-1 Transverse Spin Physics at RHIC

  21. (C) Transverse Spin Physics Channels at RHIC II and e-RHIC RHIC II J.Ralston and D.E. Soper, Nucl. Phys. B152, 109(1979) EIC Drell Yan 8fb-1, large acceptance detector for Drell Yan Transverse Spin Physics at RHIC

  22. Collins Effect in SIDIS at e-RHIC Projected errors on A in 5 z- bins Transverse Spin Physics at RHIC

  23. Summary • All instrumentation for polarized proton collisions has been installed: Unique tool to study proton structure! • First results on AN  2005 precision measurements comparisons between pions, kaons and protons • Broad program with transverse spin with increasing luminosity: AN in inclusive hadrons and jet production Sivers type back-to-back correlation between jets AT for Collins and IFF analysis AT and ATT for Drell Yan o Supporting effort to measure spin dependent fragmentation functions at Belle (RBRC/UIUC) Transverse Spin Physics at RHIC

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