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Structure and spin of the nucleon

Structure and spin of the nucleon. Harut Avakian(JLab ). focus on increasing theoretical and experimental support for the nucleon and nuclear 3D PDF programs worldwide model-independent procedure for the flavor decomposition. Gluon polarization. With upper limit may saturate the sum rule.

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Structure and spin of the nucleon

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  1. Structure and spin of the nucleon Harut Avakian(JLab) • focus on increasing theoretical and experimental support for the nucleon and nuclear 3D PDF programs worldwide • model-independent procedure for the flavor decomposition H. Avakian, Como, June 10

  2. Gluon polarization With upper limit may saturate the sum rule No need for orbital momentum? H. Avakian, Como, June 10

  3. BNL FNAL Polarised Target mbeam Drell-Yan a test of QCD P1 P2 SeaQuest Spectrometer Low Drell-Yan cross section requires a high intensity beams Nuclotron based Ion Collider fAcility • Clean probe to study hadron structure: • convolution of parton distributions • no QCD final state effects • no fragmentation process H. Avakian, Como, June 10

  4. FNAL Drell-Yan projections P1 4<M<9 GeV/c2 Drell-Yan beam results are in agreement with the simulations P2 Dc2=20 error band Boer-Mulders Sivers E-1027 Collaboration ~650k DY events 330k DY events • 3.2 x 1018 total protons (2 years) • Pb = 70% Precision measurements of DY asymmetries precision TMDs? H. Avakian, Como, June 10

  5. p SIDIS at JLab12 E. Cisbani H. Avakian, Como, June 10

  6. E12-11-108 AUT studies using SOLID Precision 4-d mapping of target SSA using SoLID and polarized NH3(p) target H. Avakian, Como, June 10

  7. H. Avakian, Como, June 10

  8. Sivers effect: p+ from EIC √s = 140 GeV, √s = 50 GeV and √s = 15 GeV EIC configurations, respectively. Event counts correspond to an integrated luminosity of 30 fb−1 arXiv:1108.1713 • Large acceptance and energy range of EIC makes it ideal place to study the contributions of sea quarks to Sivers asymmetry H. Avakian, Como, June 10

  9. Extracting Sivers function from asymmetries EIC with energy setting of √s = 45 GeV and an integrated lumi of 4 fb−1 Extraction based on Gaussian Sivers, generated and then extracted with assumption of the same shape as used in generation (unclear systematics) • Invisible error bars are due to specific procedure and may be misleading. • Need realistic error bars, need decomposition procedure H. Avakian, Como, June 10

  10. flavor and spin effects on kT > B.Musch et al arXiv:1011.1213 g1q=Dq=(q+-q-)/2 P. Schweitzer et al arXiv:1210.1267 Higher probability to find a quark anti-aligned with proton spin, also more sea and d-quarks at large kT • kT-distributions of TMDs depend on flavor and spin • In medium fractions of spin and orbital momentum change (nuclear targets) 10 H. Avakian, Como, June 10

  11. flavor and spin effects on bT space distributions depend on flavor and spin (medium?) B.Pasquini et al G. Miller et al Phys.Rev.C84:045205,2011 H. Avakian, Como, June 10

  12. Higher twists Higher twists large and underlying interactions/correlations require more attention! H. Avakian, Como, June 10

  13. Summary • focus on increasing theoretical and experimental support for the nucleon and nuclear 3D PDF programs worldwide • model-independent procedure for the flavor decomposition of 3D PDFs HAVE A VERY PRODUCTIVE WEEK! H. Avakian, Como, June 10

  14. Support slides H. Avakian, Como, June 10

  15. From low PT TMDs to high PT collinear Matching the angular integrated cross section at low PT to fixed order pQCD collinear factorization calculations at high PT Transverse momentum dependent Q>>PT>=LQCD Collinear Q,PT>>LQCD LQCD<< PT<<Q PT Georgi Politzer Collinear/ Twist-2 Twist-3 Cahn Leading Twist PT Efremov, Teryaev; Qiu, Sterman Higher Twist Collinear/ twist-3 Twist-2 Sivers PT H. Avakian, Como, June 10

  16. Correlations of spin, longitudinal and transverse degrees • What are the kT distributions of partons? • Do they depend on spin and flavor of partons? • Do they modify in medium, and how ? • How studies of proton transverse structure will improve our understanding of medium effects? • How studies of medium modifications will improve our understanding of the proton structure? • Possible new tools: • Polarized DIS resolve the spin effects in medium • Polarized and unpolarized SIDIS resolve flavor and spin effects H. Avakian, Como, June 10

  17. Kinematic correlations at finite Q2 From energy/momentum conservation arXiv: 1106.6177 energy of the parton have to be less than the energy of the parent hadron x and kT are not independent at low Q2 even in factorized Gaussian approach! H. Avakian, Como, June 10

  18. Medium modified spin observables (NJL model) I. Cloet EMC effect essentially a consequence of binding at the quark level H. Avakian, Como, June 10

  19. Transverse densities in the nucleon in nuclear matter Quark transverse charge densities inside an unpolarized proton arXiv:1304.5926 (Yakhshiev & Kim ) Skyrme model proton medium • form factors of the nucleon fell off faster in nuclear matter • the size of the nucleon tends to bulge out in nuclear matter.

  20. The Multi-Hall SIDIS Program at 12 GeV M. Aghasyan, K. Allada, H. Avakian, F. Benmokhtar, E. Cisbani, J-P. Chen, M. Contalbrigo, D. Dutta, R. Ent, D. Gaskell, H. Gao, K. Griffioen, K. Hafidi, J. Huang, X. Jiang, K. Joo, N. Kalantarians, Z-E. Meziani, M. Mirazita, H. Mkrtchyan, L.L. Pappalardo, A. Prokudin, A. Puckett, P. Rossi, X. Qian, Y. Qiang, B. Wojtsekhowski for the Jlab SIDIS working group • The complete mapping of the multi-dimensional SIDIS phase space will allow a comprehensive study of the TMDs and the transition to the perturbative regime. • Flavor separation will be possible by the use of different target nucleons and the detection of final state hadrons. • Measurements with pions and kaons in the final state will also provide important information on the hadronization mechanism in general and on the role of spin-orbit correlations in the fragmentation in particular. • Higher-twist effects will be present in both TMDs and fragmentation processes due to the still relatively low Q2 range accessible at JLab, and can apart from contributing to leading-twist observables also lead to observable asymmetries vanishing at leading twist. These are worth studying in themselves and provide important information on quark-gluon correlations. H. Avakian, Como, June 10

  21. Sivers TMD evolution Drell-Yan SIDIS Aybat, Prokudin & Rogers C12-11-111 TMD Evolution may explain existing differences between HERMES and COMPASS . Aybat, Prokudin & Rogers : arXiv:1112.4423 Comparison of JLab12 data with HERMES and COMPASS will pin down the Q2 evolution of Sivers asymmetry. H. Avakian, Como, June 10

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