分类: 物理学 >> 核物理学 提交时间: 2016-08-31
摘要: We compute the s−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−s¯ difference. Using a regularization procedure that preserves chiral symmetry and Lorentz invariance, we find that existing data limit the integrated value of the first moment of the asymmetry to the range −0.07×10−3≤⟨x(s−s¯)⟩≤1.12×10−3 at a scale of Q2=1GeV2. In contrast to some suggestions in the literature, the magnitude of this correction is too small to account for the NuTeV anomaly.