arXiv 1602.066462016-02nucl-thhep-lathep-ph

手性有效理论中质子$s-\bar s$不对称性的限制

Constraints on $s-\bar s$ asymmetry of the proton in chiral effective theory

X. G. Wang, Chueng-Ryong Ji, W. Melnitchouk, Y. Salamu, A. W. Thomas, P. Wang

备注：: 5 pages, 4 figures
发表信息：: Phys. Rev. D 94, 094035 (2016)
DOI：: 10.1016/j.physletb.2016.09.014

摘要：

我们计算的$s-\bar s$手性有效理论中的质子不对称性，使用唯象约束的基础上现有的数据。与以前的介子云模型计算，其中占的K介子回路的贡献与壳层上的中间状态单独，这项工作包括离壳条款和接触相互作用，影响的形状的$s-\bar s$差异。我们确定了$s(x)$的类化合价组分，该组分通过$δ$ -功能对$x=0$处的$\bar s(x)$的贡献来平衡，使得$s$和$\bar s$在实验可及区域$x > 0$上的积分不相等。使用正则化程序，保持手征对称性和洛伦兹不变性，我们发现，现有的数据限制的积分值的范围$-0.07 \times 10^{-3} \leq \langle x(s-\bar s) \rangle \leq 1.12 \times 10^{-3}$的不对称性的二阶矩的范围内的$Q^2=1 $ GeV $^2$。这太小了，无法解释NuTeV异常和错误的符号来增强它。

英文摘要：

We compute the $s-\bar s$ asymmetry in the proton in chiral effective theory, using phenomenological constraints based upon existing data. Unlike previous meson cloud model calculations, which accounted for kaon loop contributions with on-shell intermediate states alone, this work includes off-shell terms and contact interactions, which impact the shape of the $s-\bar s$ difference. We identify a valence-like component of $s(x)$ which is balanced by a $δ$-function contribution to $\bar s(x)$ at $x=0$, so that the integrals of $s$ and $\bar s$ over the experimentally accessible region $x > 0$ are not equal. Using a regularization procedure that preserves chiral symmetry and Lorentz invariance, we find that existing data limit the integrated value of the second moment of the asymmetry to the range $-0.07 \times 10^{-3} \leq \langle x(s-\bar s) \rangle \leq 1.12 \times 10^{-3}$ at a scale of $Q^2=1 $GeV$^2$. This is too small to account for the NuTeV anomaly and of the wrong sign to enhance it.

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