= Mean-field closure for velocity alignment
{title2=$p_2(z,z_\star)\simeq p_1(z)p_1(z_\star)$}
Neglect of pair correlations closes the first marginal equation of the <dissipative Liouville equation>. For unit-normalized <marginal distributions>, the acceleration is $(N-1)\mathbf L[p_1]$. With number-normalized $f=Np_1$, it is $(1-1/N)\mathbf L[f]$. The usual <mean-field alignment equation> neglects this relative $1/N$ correction. Independence at one time does not imply that interactions preserve independence.
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