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MENU2004, Bejing, August 29- September 5, 2004

MENU2004, Bejing, August 29- September 5, 2004. Λ POLARISATION TO PROBE N STRUCTURE. Raimondo Bertini Dipartimento di Fisica ``A. Avogadro'' and INFN - Torino, Italy. Transverse polarisation , normal to the production plane [1]. strong p T dependence:

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MENU2004, Bejing, August 29- September 5, 2004

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  1. MENU2004, Bejing, August 29- September 5, 2004 Λ POLARISATION TO PROBE N STRUCTURE Raimondo Bertini Dipartimento di Fisica ``A. Avogadro'' and INFN - Torino, Italy

  2. Transverse polarisation , normal to the production plane [1] • strong pT dependence: • increase with pT up to • ~1GeV/c, then constant • strong xF dependence: • near with xFlinear increase of  polarisation in inclusive hadron production [1]L. G. Pondrom, Phys. Rep. 122(1985)57

  3. Transverse polarisation , normal to the production plane [1]  polarisation in inclusive hadron production • polarisation magnitude • indipendent of beam energy [1]L. G. Pondrom, Phys. Rep. 122(1985)57

  4. polarisation transfer: CFR TFR

  5. Hyperon production Spin Asymmetries • production in unpolarised pp-collision: Several theoretical models: • Static SU(6) + spin dependence in parton fragmentation/recombination [1-3] • pQCD spin and transverse momentum of hadrons in fragmentation [4] • [1] T.A.DeGrand et al.,Phys. Rev D23 (1981) 1227. • [2] B. Andersoon et al., Phys. Lett. B85 (1979) 417. • [3] W.G.D.Dharmaratna, Phys. Rev. D41 (1990) 1731. • [4] M. Anselmino et al.,Phys. Rev. D63 (2001) 054029. Analysing power Data available for DNN: 3.67 GeV/c DNN < 0 13.3 -18.5 GeV/c DNN~ 0 200 GeV/c DNN > 0 DNN @ 40 GeV/c MISSING Depolarisation Key to distinguish between these models

  6. κT-dependent Parton Distributions Twist-2 PDFs f1, g1 studied for decades: h1 essentially unknown

  7. Λ polarisation with longitudinally polarised lepton beam along ê³

  8. Unpolarised beam and longitudinally pol. target Transverselly polarised target

  9. Assuming u-quark dominance R. L. Jaffe Phys. Rev. D54 (1996) R6581

  10. Semi-inclusive deep inelastic scattering

  11. Hyperon production Spin Asymmetries Polarised target: . Transverse target polarisation Existing data: PS185 (LEAR) [2] [1] K.D. Paschke et al., Phys. Lett. B495 (2000) 49. [2] PS185 Collaboration, K.D: Paschke et al., Nucl. Phys. A692 (2001) 55. [1] complete determination of the spin structure of reaction Models account correctly for cross sections. Models do not account for or . NEW DATA NEEDED

  12. Open Charm ΔG longitudinally polarised • Open charm from production • and subsequent weak decay • low branching ratio: B.R. = 0.9% • huge self-analysing asymmetry: [1] Smith Vogt Z. Phys. C75 (1997)271

  13. Beam and Target Key features: Generation of intense, high-quality secondary beams of rare isotopes and antiprotons. Two rings: simultaneous beams. SIS 100 Tm SIS 300 Tm U: 35 AGeV p: 90 GeV

  14. Drell-Yan Di-Lepton Production Scaling: Full x1,x2 range . needed [1] Anassontzis et al., Phys. Rew. D38 (1988) 1377

  15. Drell-Yan Di-Lepton Production Why Drell-Yan? Asymmetries depend on PD only (SIDIS→convolution with QFF) Why ? Each valence quark can contribuite to the diagram Kinematics

  16. Drell-Yan Asymmetries — Polarised beam and target Uncorrelated quark helicities access chirally-odd functions TRANSVERSITY • Ideal because: • h1 not to be unfolded with fragmentation functions • chirally odd functions • not suppressed (like in DIS)

  17. Drell-Yan Asymmetries — Polarised beam and target

  18. Drell-Yan Asymmetries — Unpolarised beam, polarised target λ 1,   0 Even unpolarised beam is a powerful tool to investigate кT dependence of QDF D. Boer et al., Phys. Rev. D60(1999)014012.

  19. Phase space for Drell-Yan processes  = const: hyperbolae xF = const: diagonal 15 GeV/c PANDA 30 GeV/c ASSIA 40 GeV/c

  20. Drell-Yan Asymmetries — Unpolarised beam, polarised target λ 1,   0 Even unpolarised beam is a powerful tool to investigate кT dependence of QDF D. Boer et al., Phys. Rev. D60(1999)014012.

  21. A. Bianconi (ASSIA col.)

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