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Published byAlfredo Villalobos Medina Modified over 6 years ago
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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
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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.
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Kinematics for ・Lorentz invariants: with
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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.
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Large p_T hadron production
in perturbative QCD (twist-2) diagrams Fragmentation insertion
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Cross Section: for for Characteristics:
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Azymuthal asymmetries:
O: Unpolarized, L: Long. pol.
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Sample Calculation of Azymuthal Asymmetries:
Chosen Kinematic variables: ・COMPASS energy: “Valence” region ・EIC energy: “Sea” region
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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:
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Summary
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★Cross section formula
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