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Intrinsic transverse momentum and the Sivers effect #

Intrinsic transverse momentum and the Sivers effect #. Intrinsic transverse momentum of quarks Why it is actual Cahn effect Single target spin asymmetries Sivers effect Collins effect. Aram Kotzinian Torino University & INFN On leave in absence from YerPhI, Armenia and JINR, Russia.

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Intrinsic transverse momentum and the Sivers effect #

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  1. Intrinsic transverse momentum and the Sivers effect # • Intrinsic transverse momentum of quarks • Why it is actual • Cahn effect • Single target spin asymmetries • Sivers effect • Collins effect Aram Kotzinian Torino University & INFN On leave in absence from YerPhI, Armeniaand JINR, Russia • In collaboration with M. Anselmino, M. Boglione, U. D'Alesio, F. Murgia & A. Prokudin AramKotzinian

  2. SIDIS AramKotzinian

  3. Intrinsic transverse momentum role Gluon polarization measurement LP QCDCompton PGF R strongly depends on the intrinsic and fragmentation AramKotzinian

  4. Unpolarized SIDIS & Cahn effect AramKotzinian

  5. approximation Ji et al: QCD factorization holds for AramKotzinian

  6. Comparison with data EMC, 280 GeV muon SIDIS AramKotzinian

  7. Hadron transverse momentum dependence AramKotzinian

  8. Collins Effect Side view Front view Up-Down asymmetry = 0 Nonzero Left-Right asymmetry azimuthal modulation of transversely polarized quark FF Schaefer-Teryaev SR: hadrons transverse momenta are compensated in the quark fragmentation AramKotzinian

  9. Sivers Effect Azimuthal modulation of quark transverse momentum for a transversely polarized nucleon Unpolarized DF: Polarized DF: Quark transverse momentum is compensated by that of target remnant AramKotzinian

  10. SSA Analysis by Anselmino et al, E704 Only Collins effect Only Sivers effect Analyzing power: STAR AramKotzinian

  11. HERMES SSA One can describe the data using only Collins effect Schweitzer & Bacchetta: there is a room for Sivers effect Efremov, Goeke &Schweitzer: one can neglect the Sivers effect AramKotzinian

  12. Parameterization for Sivers effect AramKotzinian

  13. Anselmino et al for E704 SSA u-quark d-quark Our parameterization: opposite sign & high values at small x AramKotzinian

  14. Results: p on P & D targets AramKotzinian

  15. Results: K on D target AramKotzinian

  16. AramKotzinian

  17. AramKotzinian

  18. Quark intrinsic transverse momentum in LEPTO - Generate virtual photon – quark scattering in collinear configuration: - Before - After - Generate intrinsic transverse momentum of quark (Gaussian) - Rotate - Generate uniform azimuthal distribution of quark - Rotate - Generate quark azimuthal angle according to Sivers distribution AramKotzinian

  19. Modified LEPTO MC predictions for JLAB SSA Opposite signs of asymmetry in the target and current fragmentation In principle, one can check origin of by measuring it in the TFR AramKotzinian

  20. Electron Ion Collider AramKotzinian

  21. Modified LEPTO MC predictions for EIC SSA Opposite signs of asymmetry in the target and current fragmentation In principle, one can check origin of by measuring it in the TFR AramKotzinian

  22. End of Story? Zoology of FracFun AramKotzinian

  23. Conclusions • Intrinsic transverse momentum in simple parton model approach allows to describe • Hadron transverse momentum dependence in SIDIS • Cahn effect • HERMES SSA data on longitudinally polarized target • It is important to investigate the SSA in the TFR • Sivers effect? • Collins effect from target remnant hadronization? • We need more precise data on transversely polarized targets AramKotzinian

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