Constraints on the s - (s)over-bar asymmetry of the proton in chiral effective theory

We compute the s - (s) over bar 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) over bar difference. We identify a valence-like component of s(x) which is balanced by a delta-function contribution to (s) over bar (x) at x = 0, so that the integrals of sand (s) over bar 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 x 10(-3) <= < x(s - (s) over bar)> <= 1.12 x 10(-3) at a scale of Q(2) = 1 GeV2. This is too small to account for the NuTeV anomaly and of the wrong sign to enhance it. (C) 2016 The Authors. Published by Elsevier B.V.