摂動ＱＣＤに基づくシングルスピン非対称研究の現状 ーツイスト３機構の立場からー 小池裕司（新潟大学） 第１回高エネルギーQCD・核子構造勉強会 2014年2月4日＠理研，和光

FNAL-E704 P.L. B264 (’91) 462 P.L. B261 (’91) 201

★ RHIC-STAR (‘04) ★ RHIC-BRAHMS (‘07) First, we have to confirm the validity of the perturbative calculation .

- Graphical representation of the 1st , 2nd and 3rd terms : Qiu, Sterman (‘99), Kouvaris et.al.(‘06),YK-Tomita(‘09), Kanazawa-YK(‘10) Beppu,YK,Kanazawa,Yoshida(‘13) Kang, Yuan, Zhou (‘10), Metz, Pitonyak,(‘12) Kanazawa, Koike (‘00) ⇒ The last term can be ignored. - Graphical representation of the 1st , 2nd and 3rd terms : In this process, there are three nonperturbative functions. So, the twist-3 contributions to the spin dependent cross-section are obtaind by replacing a twist-2 distribution or fragmentation function by corresponding twist-3 distribution of fragmentation functions. So, two resaonable contribution to the SSA. The calculation is implete.

- Reasonable description of SSA for pions and kaons with this formula: Koike-Tomita (2009) Kouvaris-Qiu-Vogelsang-Yuan (2006) - Reasonable description of SSA for pions and kaons with this formula: KK-Koike (2010)

PT dependence is well reproduced : ★ STAR (2008) PT dependence is well reproduced : ⇒

★ Decomposition of the asymmetries into each fragmentation channel - The difference comes from the strange components.