200 GeV极化质子对撞产物π<sup>0</sup>单自旋不对称性

200 GeV极化质子对撞产物π⁰单自旋不对称性

摘要: 为了解核子自旋结构函数，本文研究了极化质子碰撞过程中介子产物π⁰粒子的单自旋不对称。RHIC/PHENIX Run8数据横动量p_T覆盖范围为1～7 GeV/c，由于质心能量和极化度的大幅提高，其π⁰单自旋不对称度较Run2数据的小3个数量级。π⁰单自旋不对称度随能量和极化度的提高而下降的现象表明胶子Sivers分布得到进一步紧缩，为pQCD的预测结果提供了新的证据。

Abstract: To understand the nuclear spin structure function, the single spin asymmetry ofπ⁰ produced in collision of polarized proton was researched. The single spin asymmetry of π⁰, produced in polarized proton-proton collisions at 200 GeV, has been drawn from RHIC Run8 data, which covers a p_T range of 1-7 GeV/c. Due to the higher rates and the higher beam polarization, the preliminary result is smaller with 3 orders of magnitude than Run2. This phenomenon implies a constraint of the Sivers distribution of gluons calculated by pQCD theory.