Chiral symmetry and the nucleon spin structure functions
Chiral symmetry and the nucleon spin structure functions
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手性对称性和核子自旋结构函数
DOI：
10.1103/physrevd.60.034020
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发表时间：
1998
影响因子：
5
通讯作者：
T. Kubota
中科院分区：
文献类型：
--
作者：
M. Wakamatsu;T. Kubota
本文通过对手性夸克孤子模型（CQSM）中手性对称性的作用的特别关注，系统地研究了手性夸克孤子模型（CQSM）框架内核子的扭转-双自旋相关结构函数。手性对称性的重要性是通过对中子自旋结构函数${g}_{1}^{n}{(x,Q}^{2}).$的最新SLAC数据的良好再现来说明的。我们还观察到纵向极化分布函数的预测与横向分布函数的预测之间存在实质性差异。手性对称性可能是造成这种差异的原因，这可以从相应第一矩的同位旋依赖性中看出，即轴向和张量电荷。CQSM预测等标量与等矢量轴电荷之比为${g}_{A}^{(0)}{/g}_{A}^{(3)}\ensuremath{\simeq}0.25$，而等标量与等矢量张量电荷之比为${g}_{T}^{(0)}{/g}_{T}^{(3)}\ensuremath{\simeq}0.46$，这应该与成分夸克模型或未适当考虑手性对称性的朴素MIT袋模型的预测${g}_{A}^{(0)}{/g}_{A}^{(3)}{=g}_{T}^{(0)}{/g}_{T}^{(3)}=3/5$进行比较。CQSM的另一个突出预测是$\ifmmode \bar{u}\else ū\fi{}$和$\overline{d}$反夸克的相反极化，从而表明核子中的SU(2)不对称海夸克（自旋）极化。
We carry out a systematic investigation of twist-two spin dependent structure functions of the nucleon within the framework of the chiral quark soliton model (CQSM) by paying special attention to the role of chiral symmetry of QCD. The importance of chiral symmetry is illustrated through the good reproduction of the recent SLAC data for the neutron spin structure function ${g}_{1}^{n}{(x,Q}^{2}).$ We also observe a substantial difference between the predictions of the longitudinally polarized distribution functions and those of the transversity distribution functions. That the chiral symmetry may be responsible for this difference is seen in the isospin dependence of the corresponding first moments, i.e., the axial and tensor charges. The CQSM predicts ${g}_{A}^{(0)}{/g}_{A}^{(3)}\ensuremath{\simeq}0.25$ for the ratio of the isoscalar to isovector axial charges, while ${g}_{T}^{(0)}{/g}_{T}^{(3)}\ensuremath{\simeq}0.46$ for the ratio of the isoscalar to isovector tensor charges, which should be compared with the prediction ${g}_{A}^{(0)}{/g}_{A}^{(3)}{=g}_{T}^{(0)}{/g}_{T}^{(3)}=3/5$ of the constituent quark model or of the naive MIT bag model without proper account of chiral symmetry. Another prominent prediction of the CQSM is the opposite polarization of the $\ifmmode \bar{u}\else \={u}\fi{}$ and $\overline{d}$ antiquarks, thereby indicating the SU(2) asymmetric sea quark (spin) polarization in the nucleon.