= Neutrino-antineutrino DIS sea momentum ratio
{title2=$\bar Q/Q=(3R-1)/(3-R)$}
For an <Isoscalar target>[isoscalar target] in the leading massless quark-parton approximation, integrate the two <helicity> weights over <inelasticity>: $\int_0^1dy=1$ and $\int_0^1(1-y)^2dy=1/3$. Then $R=\sigma_{\bar\nu}/\sigma_\nu=(Q/3+\bar Q)/(Q+\bar Q/3)$, where $Q=\int xq(x)dx$ and $\bar Q=\int x\bar q(x)dx$. Inversion gives the displayed ratio. These are effective weak-flavour <momentum> fractions; the data do not determine unweighted <parton> number integrals.
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