1. Single-spin asymmetry of charm di-jet in longitudinally polarized pp collisions at STAR Introduction and motivation Reconstruction of W and Z signals Single-spin asymmetry of di-jet Summary and outlook

2. Nucleons’ spin structure Spin sum rule for nucleon: In naive Quark Model, the nucleon is made up of three quarks, its spin (½) is carried by the three quarks’ spin. “Spin Crisis” : In 1988, EMC experiment found proton spin carried by quarks’ spin is 20%-30%. Orbital Angular Momentum Introduction and motivation

3. Longitudinal spin program at RHIC

4. Introduction and motivation SSA of W bosons Leading order diagrams for

5. Introduction and motivation SSA of W bosons

6. Introduction and motivation SSA of W bosons Motivation-----1

7. Introduction and motivation Reconstruction of W Leptonic channel :Hadronic channel :

8. Introduction and motivation Leptonic channel

9. Introduction and motivation Hadronic channel Motivation-----2

10. Introduction and motivation SSA of di-jet

11. Reconstruction of W and Z signals UA2 experiment R.Ansari et al [UA2 Collaboration], Phys. Lett. B 186, 452 (1987)

12. Reconstruction of W and Z signals Fast Simulation of the invariant mass distribution of di-jet in pp collision at STAR. Mass resolution : 5%

13. Fast simulation of the invariant mass distribution of charm di-jet in pp collision at STAR. Reconstruction of W and Z signals Mass resolution : 5%

14. From W+From W-From Z0QCD 2->2W+/total common di-jet592561976442007.04E+60:0083 charm di-jet2923699247041.92E+50:126 cross section: comparison: Reconstruction of W and Z signals

16. Single-spin asymmetry of di-jet SSA of pure W bosons

17. Single-spin asymmetry of di-jet SSA of di-jet

18. Single-spin asymmetry of di-jet SSA of charm di-jet

19. Single-spin asymmetry of di-jet SSA of charm di-jet events & the charge of charm can be determined

20. Summary and outlook Summary

21. Summary and outlook Outlook

25. Why D LL of (anti-)lambda in STAR? Longitudinal spin transfer in polarized proton-proton collisions: Pol. frag. func. model Q. X, E. Sichtermann, Z. Liang, PRD 73,2006 Theory prediction on polarization of anti-lambda in RHIC energy:

26.  ~ 1.3 GeV  ~ 0.0075 Data sample:  Minbias data from run 2005  About 3M events Kinetics range: Qinghua Xu for STAR

28. Jet define algorithms: Kt algorithms and cone algorithms See Salam’s talk

29. RHIC : Relativistic Heavy Ion Collider STAR : The Solenoidal Tracker at RHIC TPC : time projection chamber EMC : E-M calorimeter