1. March 16, 2004@J-Lab meeting Y. Koike (BNL/Niigata Univ.)
Azymuthal Spin Asymmetries for Large P_T
Hadron Production at eRHIC
March 16, meeting
Y. Koike (BNL/Niigata Univ.)
Cf. Y.K. and J. Nagashima, NPB660(2003) 269

2. Azymuthal asymmetry for large- hadron production in SIDIS
Double spin asymmetries: twist-2
Cf.
-integrated cross sections:
LO; Ji(’94).
NLO; de Florian et al (’96), Stratmann(’96), Vogelsang(’96),…
-differential cross section with intrinsic k_T:
LO, Mulders&Tangerman(’96), Boer&Mulders(’98), …
This is relevant only for small p_T production.

4. Kinematics for
・Lorentz invariants:
with

5. Hadron frame for (Meng, Olness, Soper(’91)) photon-proton Breit frame
mom. of hadron B
Azymuthal angle between
lepton and hadron plane
Spin vector
Polar angle of
Azymth. Measured from hadron plane.

6. Large p_T hadron production
in perturbative QCD (twist-2)
diagrams
Fragmentation
insertion

7. Cross Section:
for
for
Characteristics:

9. Azymuthal asymmetries:
O: Unpolarized, L: Long. pol.

10. Sample Calculation of Azymuthal Asymmetries:
Chosen Kinematic variables:
・COMPASS energy:
“Valence” region
・EIC energy:
“Sea” region

11. Sample Calculation of Azymuthal Asymmetries:
・ GRV98
・　　　　　 GRSV2000 (std. and val.), AAC (’00), GS(’96)
・ Ansatz
N.B. Very crude estimate. Their evolution is different.
・ fragmentation function: KKP2000, Kretzer(’00)
・ fragmetation function: DSV98 (de Florian et al)
Three scenarios for long. pol. fragmentation function:
At low energy input scale they are constructed such that
scen.1: (NR quark model)
scen.2: (inspired by Burkardt-Jaffe)
scen.3:
Transversity fragmentation function:

18. Summary

23. ★Cross section formula