Constraints on the asymmetry of the proton in chiral effective theory

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• 作者：X.G. Wang^a ; Chueng-Ryong Ji^b ; W. Melnitchouk^c ; ^{wmelnitc@jlab.org" class="auth_mail" title="E-mail the corresponding author} ; Y. Salamu^d ; A.W. Thomas^a ; P. Wang^d ; ^e
• 关键词：Strange asymmetry ; Chiral symmetry ; Kaon loops
• 刊名：Physics Letters B
• 出版年：2016
• 出版时间：10 November 2016
• 年：2016
• 卷：762
• 期：Complete
• 页码：52-56
• 全文大小：373 K

文摘

We compute the $s-\overline{s}$ 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 $s-\overline{s}$ difference. We identify a valence-like component of s(x)$s(x)$ which is balanced by a δ  -function contribution to $\overline{s}(x)$ at ddafeb5abea74dbf488dd" title="Click to view the MathML source">x=0$x=0$, so that the integrals of s   and $\overline{s}$ over the experimentally accessible region x>0$x>0$ 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 $-0.07\times {10}^{-3}\le 〈x(s-\overline{s})〉\le 1.12\times {10}^{-3}$ at a scale of Q²=1 GeV²$Q^2=1{\text{GeV}}^2$. This is too small to account for the NuTeV anomaly and of the wrong sign to enhance it.