Jäger Barbara, Stratmann Marco, Kretzer Stefan, Vogelsang Werner
Institut für Theoretische Physik, Universität Regensburg, D-93040 Regensburg, Germany.
Phys Rev Lett. 2004 Mar 26;92(12):121803. doi: 10.1103/PhysRevLett.92.121803.
Recent preliminary PHENIX data are consistent with a negative and sizable longitudinal double-spin asymmetry A(pi)(LL) for pi(0) production at moderate transverse momentum p( perpendicular ) approximately 1-4 GeV and central rapidity. By means of a systematic investigation of the relevant degrees of freedom, we show that the perturbative QCD framework at leading power in p( perpendicular ) produces at best a very small negative asymmetry in this kinematic range.
近期PHENIX的初步数据与在中等横向动量(p_T)（约1 - 4 GeV）和中心快度下(\pi^0)产生的负且可观的纵向双自旋不对称性(A_{\pi}(LL))一致。通过对相关自由度的系统研究，我们表明，在(p_T)的主导幂次下的微扰量子色动力学框架在这个运动学范围内最多产生非常小的负不对称性。
