A prediction of unintegrated parton distribution

1. A prediction of unintegrated parton distribution Ruan Jianhong Zhu Wei East China Normal University

2. outline • Introduction • The models • Our scheme • Conclusion

3. 1 Introduction ① The integrated parton distributuion • evolution according to DGLAP equation, input parton distribution such as GRV,MRST,CTEQ… • can be used to describe inclusive processes • well decided by the global fit of structure function F2

4. ② the unintegrated parton distribution For less inclusive processes, the distributions unintegrated over the tranverse momentum have to be considerd.

5. 2 The models ① CCFM evolution equation: • The unintegrated gluon distribution satisfies the CCFM evolution equation based on angular ordering. • The interactions among initial partons are neglected in the CCFM equation. • The solution of the CCFM equation has only proved practically with Monte Carlo generators.

6. ② Golec-Biernat-Wusthoff gluon distribution • Based on the parametrization of the dipole-nucleon cross section with parameters fitted to the HERA data

7. ③Kharzeev-Levin gluon distribution • based on the idea of gluon saturation, the gluon distribution is parametrized. • It was claimed that the gluon distribution leads to a good description of the recent RHIC rapidity distributions.

8. ④ KMR scheme • Kimber, Martin and Ryskin proposed that the two scale UPDFs can be derived from the single-scale unintegrated distribution, and its dependence on the second scale μ is introduced by using the Sudakov factor.

9. 3 Our method: KMR scheme • MD_DGLAP • equation

12. the initial quark and gluon densities (GRV-like)

16. our result The unintegrated gluondensity in proton at μ=10 GeV

17. The unintegrated gluondistributions in Pb(A=208)

18. Comparison of our predicted (RZ)-gluon(solid curves) with other models

19. Published in physics review c 80,045209(2009)

20. Particle multiplicities and limiting fragmentation ① Two component model Ⅰcentral region gg →g mechanism quark recombination model Ⅱ fragmentation region

21. Ⅰcentral region Ⅱfragmentation region

22. Proton-proton collisions

26. ② Fragmentation limiting

29. 5 Conclusion: ① we predict the unintegrated parton distributions in proton and nucleus by using the KMR scheme incorporating the shadowing and antishadowing corrections ②We find that the suppression of the unintegrated gluon distribution when kt→0 arises from the valence-like input rather than the nonlinear saturation effect, although the nonlinear shadowing effect is obvious. ③We use two complementary production mechanisms: hard gluon-gluon fusion in the central rapidity region and soft quark recombination in the fragmentation region to study the particle multiplicity distributions in hadron-hadron collisions at high energies. ④We find that the limiting fragmentation hypothesis, which generally appear in present data of hadron collisions is partly violated if the observations are across over a wide range between the RHIC-LHC energies.

30. Thank You!