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Energy Evolution for the Sivers Asymmetries in Hard Processes

Energy Evolution for the Sivers Asymmetries in Hard Processes. Peng Sun LBNL in collaboration with F Yuan arXiv: 1304.5037. Outlines. TMD factorization Energy evolution Fit the sivers function with SIDIS experiments Implement the TMD evolution from low Q SIDIS to Drell-Yan

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Energy Evolution for the Sivers Asymmetries in Hard Processes

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  1. Energy Evolution for the SiversAsymmetries in Hard Processes Peng Sun LBNL in collaboration with F Yuan arXiv: 1304.5037

  2. Outlines TMD factorization Energy evolution Fit the sivers function with SIDIS experiments Implement the TMD evolution from low Q SIDIS to Drell-Yan Collins asymmetries 2014/9/5 2

  3. TMD factorization • TMD factorization is an extension and simplification to the collinear factorization • Simplifies the kinematics • Power counting, correction 1/Q neglected (PT,Q)=H(Q) f1(x1,k1T,Q) f2(x2,k2T, Q) S(T) • There is no x- and kT-dependence in the hard factor 2014/9/5 3

  4. Energy evolution By solving CSS evolution equations At the leading order of ɑs

  5. There is no Landau pole singularity in the integral • Almost parameter-free • No Q-dependent non-perturbative form factor • Gaussian assumption at lower scale Q0 2014/9/5 6

  6. SIDIS Q2=3.14GeV2 X=0.16 SIDIS at HERMES g0=0.1, gh=0.045 Q2=3.14GeV2, x=0.16 2014/9/5 7

  7. SIDIS at COMPASS, Q2=7.75, x=0.1

  8. Drell-Yan 2014/9/5 9

  9. Fit to Sivers asymmetries With the evolution effects taken into account. Not so large Q difference 2014/9/5 10

  10. Uncertainties in the Sivers functions: moments Up quark most constrained in the moderate x Large uncertainties in small-x region and sea quark 2014/9/5 14

  11. Predictions at RHIC About a factor of 2 reduction, as compared to previous order of magnitude difference 2014/9/5 15

  12. Collins asymmetries in e+e-→hh The collins effect is porprotianal to cos(2ɸ0)

  13. Collins asymmetries Ec.m.≈10GeV, di-hadron azimuthal asymmetric correlation in e+e- annihilation 2014/9/5 17

  14. Test the evolution at BEPC Ec.m.=4.6GeV, di-hadron in e+e- annihilation BEPC-(Beijing electron-positron collider) 2014/9/5 18

  15. Conclusion We evaluate the energy dependence for Sivers asymmetries in hard processes, from HERMES/COMPASS to typical Drell-Yan process The same evolution procedure consistently describes the Collins asymmetries from HERMES/COMPASS and BELLE Further tests are needed to nail down this issue 2014/9/5 19

  16. Thank you very much!

  17. Structure function is • Ji Ma Yuan scheme, in SIDIS It depends on ρ

  18. Collins scheme This version is much simpler than that of Ji Ma Yuan

  19. In Aybat-Collins-Qiu-Rogers framework And then Here gK(b) is gc×b2

  20. Energy Evolution in TMD factorization scheme Aybat-Collins-Qiu-Rogers, 2011

  21. Q2-dependence Needs a cross check! Aybat-Prokudin-Rogers, 2011 2014/9/5 25

  22. Collins asymmetries in SIDIS asd 2014/9/5 26

  23. Energy evolution In our framework At the leading order of ɑs

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