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Transverse Single Spin Asymmetries in PHENIX (♯)

29 th Workshop on Nuclear Dynamics Squaw Valley, CA, Feb. 3-10, 2013. Transverse Single Spin Asymmetries in PHENIX (♯). K. Oleg Eyser. The Proton Spin Structure. momentum. momentum. Eur. Phys. J. A39, 89 (2009 ). What is the connection to orbital angular momentum?

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Transverse Single Spin Asymmetries in PHENIX (♯)

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  1. 29th Workshop onNuclear Dynamics Squaw Valley, CA, Feb. 3-10, 2013 Transverse Single Spin Asymmetries in PHENIX(♯) K. Oleg Eyser

  2. The Proton Spin Structure momentum momentum Eur. Phys. J. A39, 89 (2009) What is the connection to orbital angular momentum? Transversity ↔ tensor charge  from lattice QCD

  3. y P S x Transverse Spin Asymmetries Reaction plane p0 S Beam Polarization  Azimuthal Modulation of Cross Section

  4. Transverse Spin Asymmetries • In pQCD (collinear) ANsuppressed by What is the origin of these asymmetries? Do they persist at higher energies?

  5. Proton-Proton Collisions • Initial State • pQCD • Final State fa FFq σ fb Sivers Effect Phys. Rev. D 41, 83 (1990) Correlation between proton spin & transverse parton momentum Collins Fragmentation Nucl. Phys. B396, 161 (1993) correlation between proton spin & quark spin + spin dependant fragmentation function How valid is factorization for hadronic collisions? Are the separate contributions universal?

  6. Higher Twist X. Ji, J.-W. Qiu, W. Vogelsang, F. YuanPRL 97, 082002 (2006) • TMD parton distribution functionsvs. collinear QCD factorization soft pT breaks factorization 1 / pT shape not yet observed twist-three quark-gluon correlation functions

  7. Transverse Asymmetries Sivers effect e++e- • Inclusive hadrons • Direct photons • Jets • Jet correlations/structure • Hadron Correlations • Interference fragmentation • Drell-Yan • W-bosons TransverseAsymmetries transversity e+p Twist-3 p+p Collins effect

  8. @ RHIC Absolute Polarimeter (H jet) RHIC pCPolarimeters Siberian Snakes AnDY Spin Flipper STAR PHENIX Siberian Snakes Spin Rotators Partial Snake Strong Snake Polarized Source Helical Partial Snake LINAC AGS BOOSTER 200 MeV Polarimeter Rf Dipole AGS Internal Polarimeter AGS pCPolarimeter

  9. @ RHIC

  10. Mid-rapidity Asymmetries • 0 @ s = 200 GeV • Partonic contributions change with pT • Compare Phys. Rev. D 74, 094011

  11. Forward Asymmetries 0 processs contributionGuzeyet al, PLB 603,173 (2004) • No strong dependence on s from 19.4 ~ 200 GeV • Slight differences in pseudo-rapidity and/or pT

  12. Isospin Dependence √s = 62.4 GeV fragmentation u/d 1:0 2:1 1:1 u u Sivers Transversity d d

  13. pT Dependence PHENIX-MPC tower size 2.252 cm2 220 cm from vertex decay photon 0 direct photon • Expected 1/pT fall-off • √s = 500 GeV Projection for 2012/13

  14. Forward AN( ) √s = 200 GeV STAR • STAR sees large asymmetry at high xF(arXiv 1205.6826) • Difference in fragmentation • mass, strangeness, isospin

  15. Heavy Flavor • Highly dominated by gluon fusion • No transversity/Collins • Clean gluon Sivers

  16. Collins Asymmetries • Azimuthal asymmetry of hadrons in jets • F. Yuan, PRL 100, 032003 (2008) compare PRD 86, 039905 (2012)

  17. Interference Fragmentation • Di-hadron correlation • A. Bacchetta, M. Radici, PRD 70, 094032 (2004) • Factorization is preserved: • compare PRL 107, 072004 (2011)

  18. Direct Photons • MPC-EX upgrade arxiv:1301.1096 Ready in 2014 • p0 identification up to 80 GeV

  19. Sivers Asymmetries Drell-Yan A. Prokudin, Z.-B. Kang SIDIS

  20. The Path Forward

  21. So… where we at? • Non-vanishing transverse single spin asymmetries have been measured over a wide range of energies • Details of mechanism not finally understood • Isospin dependence • Flavor dependence • Transversity (high-x) andfundamental (p)QCD tests Is factorization valid for TMDs? Are TMDs universal? How do they evolve? How do they relate to orbital angular momentum?

  22. Know thyself!

  23. Intrinsic Parton Motion • √s = 20~100 GeV • L ≈ 1033-34 cm-2s-1 • P ≈ 70%

  24. Nucleon Tomography arxiv: 1212.1701

  25. BACKUP

  26. Heavy Flavor

  27. Jets • AnDY run 2012 • Trigger on EMCal introduces bias (high-z pion) √s = 500 GeV

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