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NLO QCD fits to polarized DIS & SIDIS data

NLO QCD fits to polarized DIS & SIDIS data. Rodolfo Sassot Universidad de Buenos Aires. Global Analysis Workshop, BNL October 8, 2007. why spin?. indispensable tool for unveiling hadron structure,. spin & unexpected physics. why polarized DIS?.

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NLO QCD fits to polarized DIS & SIDIS data

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  1. NLO QCD fits to polarized DIS & SIDIS data Rodolfo Sassot Universidad de Buenos Aires Global Analysis Workshop, BNL October 8, 2007

  2. why spin? • indispensable tool for unveiling hadron structure, • spin & unexpected physics. why polarized DIS? • historical benchmark for hadron structure, • 90’s experimental programs. why NLO QCD global fits? • QCD improved description for spin dependent processes • LO vs. NLO R. Sassot BNL, October 8, 2007

  3. why polarized SIDIS? • flavor and quark-antiquark discriminatrion, • increasead statistics, new/forthcoming data • sea quarks and flavor dependence in hadronization. what do we get from data? • fits to inclusive/semi-inclusive polarized data. • uncertainties in pPDFs: Δq, Δg. ¯ • impact “direct” Δgmeasurements. how can we improve the present picture? • further constraints from forthcoming data. • fragmentation functions. R. Sassot BNL, October 8, 2007

  4. The case for pSIDIS: pDIS flavor decomposition R. Sassot BNL, October 8, 2007

  5. The case for pSIDIS: Flavor decomposition in pSIDIS R. Sassot BNL, October 8, 2007

  6. DNS NLO combined analysis: parameterizations D. de Florian, G. Navarro , R.S. Phys.Rev.D71 094018 (2005) pDIS can probe: pSIDIS give access to: 20 parameters positivity relative to MRST02: A.D. Maritn et al. Eur.Phys.J.C28 (2002) 455 R. Sassot BNL, October 8, 2007

  7. DNS NLO combined analysis: data R. Sassot BNL, October 8, 2007

  8. Fragmentation functions input in DNS: KRE: S. Kretzer Phys.Rev.D62 054001 (2000) KKP: B. A. Kniehl, G. Kramer, B. Potter, Nucl.Phys.B582 514 (2000) flavorseparation: R. Sassot BNL, October 8, 2007

  9. DNS Results: 478-20=458 d.o.f 313 pDIS 165 pSIDIS R. Sassot BNL, October 8, 2007

  10. Uncertainties: J. Pumplin et al. Phys.Rev.D65 014011 (2002) R. Sassot BNL, October 8, 2007

  11. R. Sassot BNL, October 8, 2007

  12. Consistency with independent measurements: G. Navarro , R.S. PRD74 011502 (2006) R. Sassot BNL, October 8, 2007

  13. STAR Coll., PRL97, 252001, (2006) R. Sassot BNL, October 8, 2007

  14. Next steps: DSS FFs: kaon fragmentation, h+/h- MSTW PDFs: positivity constraints, evolution New Compass SIDIS data: flavor at low x Compass/Hermes DIS data (Q2-bin): gluon shape? RHIC data: ALL , jets: Δg R. Sassot BNL, October 8, 2007

  15. New “DSSV” pPDFs: pre-pre-pre-pre-preliminary…. NEW NEW R. Sassot BNL, October 8, 2007

  16. New “DSSV” pPDFs: pre-pre-pre-pre-preliminary why has Δs changed?? old FFs were overestimated from Daniel’s talk R. Sassot BNL, October 8, 2007

  17. R. Sassot BNL, October 8, 2007

  18. Conclusions: successfull experimental programs • pPDFs have evolved dramatically: tools for the analysis (NLO) from ‘scenarios’ to ‘constraints’ • pSIDIS opens a window to sea quarks and helps to constrain other densities consistency pDIS/pSIDIS • overall picture combined NLO global fits: improved constraints on pPDFs best fits favor small ΔgandSU(3)? • dependence on FFs as a caveat: needs improvement! new polarized data: RHIC, COMPASS, JLAB, eRHIC? • future prospects: encouraging! new generation of FFs most exciting in the spin saga: the unexpected… R. Sassot BNL, October 8, 2007

  19. Acknowledgments: A. Deshpande, W. Vogelsang RIKEN-BNL, hospitality and support. R. Sassot BNL, October 8, 2007

  20. R. Sassot BNL, October 8, 2007

  21. R. Sassot BNL, October 8, 2007

  22. R. Sassot BNL, October 8, 2007

  23. Results: D. de Florian, G. Navarro , R.S. Phys.Rev.D71 094018 (2005) 478-20=458 d.o.f 313 pDIS 165 pSIDIS Interplay between pDIS and pSIDIS R. Sassot BNL, October 8, 2007

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