= Edwards-Anderson order parameter
{c}
{title2=$q_{\rm EA}=N^{-1}\sum_i\langle s_i\rangle_\alpha^2$}
The <Edwards-Anderson order parameter> measures squared local <spin magnetization> within a selected equilibrium state $\alpha$. Squaring prevents opposite local orientations from cancelling. The state selection and limits matter: the full finite, zero-field <canonical ensemble> has $\langle s_i\rangle=0$ by <spin inversion symmetry>, so substituting that average would miss broken-state order.<50 years of spin glass theory by David Sherrington and Scott Kirkpatrick>[p. 1, replica and squared-local-moment order parameter; finite-system state selection is distinguished explicitly here]{ref}
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