Superinvariants Below Critical Loop Order

Investigation of on-shell superinvariants is the standard way to identify the candidate UV divergences in supergravity. Geometric on-shell superinvariants in 4d supergravity at $N\geq 4$ are available starting at the critical loop order. However, more than 10 years ago, it was conjectured that the UV divergences in supergravity might appear earlier, for $L=N-1$, due to the existence of harmonic superspace superinvariants based on Grassmann analytic superfields. Here we show that these harmonic superinvariants at the nonlinear level are inconsistent, because Grassmann analyticity breaks local $H$ symmetry of the $N\geq 4$ on-shell superspace. Therefore, the "puzzling enhanced cancellation" of UV divergences for $L=N-1$ in superamplitude calculations for $L=3, \, N=4$ and $L=4, \, N=5$ is explained by nonlinear local supersymmetry consistent with unbroken local $H$ symmetry.