A linear <counterterm> can be chosen so that the renormalized one-point function, or equivalently the chosen <vacuum expectation value>, is zero. This cancels attached <tadpole diagrams> in the perturbative expansion about that vacuum. In a massive <six-dimensional cubic scalar field theory>, the one-loop proper tadpole is $t=gI_1/2$; without subtraction the stationary background shifts by $v=-t/m^2+O(g^3)$ at one-loop order. One must specify this convention when comparing reducible exchange diagrams or mass corrections.


 Tadpole subtraction (source code)