= Equation-of-motion reduction of scalar operators
{title2=$\Box\phi\doteq-m^2\phi-\lambda\phi^3/6$}
At first order in the suppression of an <effective operator>, a factor of the leading <Euler-Lagrange field equation> defines a <redundant operator> removable by a local <field redefinition>. For $\mathcal L_0=(\partial\phi)^2/2-m^2\phi^2/2-\lambda\phi^4/24$, one obtains $\phi^3\Box\phi\doteq-m^2\phi^4-\lambda\phi^6/6$ and $(\Box\phi)^2\doteq m^4\phi^2+m^2\lambda\phi^4/3+\lambda^2\phi^6/36$. Lower-dimensional parameter shifts must accompany this reduction when $m\ne0$; it is not an identity for untransformed <off shell> <correlation functions>.
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