1 / 27

Energy Evolution for the Sivers Asymmetries in Hard Processes

This paper discusses the energy evolution and TMD factorization relevant to Sivers asymmetries observed in hard scattering processes. We outline the approach of TMD factorization as a simplification that extends conventional collinear factorization, providing insights into the kinematic aspects of SIDIS and Drell-Yan processes. We present fits of the Sivers function using data from HERMES and COMPASS, taking evolution effects into account, and evaluate its uncertainties. Furthermore, we explore connections to Collins asymmetries and propose further checks to validate the consistency of our framework.

qabil
Télécharger la présentation

Energy Evolution for the Sivers Asymmetries in Hard Processes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related