Abstract. When quantum supergravity is studied on manifolds with boundary, one may consider local boundary conditions which fix on the initial surface the whole primed part of tangential components of gravitino perturbations, and fix on the final surface the whole unprimed part of tangential components of gravitino perturbations. This paper studies such local boundary conditions in a flat Euclidean background bounded by two concentric 3-spheres. It is shown that, as far as transverse-traceless perturbations are concerned, the resulting contribution to ζ(0) vanishes when such boundary data are set to zero, exactly as in the case when non-local boundary conditions of the spectral type are imposed. These properties may be used to show that one-loop finiteness of massless supergravity models is only achieved when two boundary 3-surfaces occur, and there is no exact cancellation of the contributions of gauge and ghost modes in the Faddeev-Popov path integral. In these particular cases, which rely on the use of covariant gauge-averaging functionals, pure gravity is one-loop finite as well.
Local Boundary Conditions in Quantum SupergravityThe problem of a consistent formulation of quantum supergravity on manifolds with boundary is still receiving careful consideration in the current literature [1][2][3][4]. In particular, many efforts have been produced to understand whether simple supergravity is one-loop finite (or even finite to all orders of perturbation theory [3]) in the presence of boundaries.In the analysis of such an issue, the first problem consists, of course, in a careful choice of boundary conditions. For massless gravitino potentials, which are the object of our investigation, these may be non-local of the spectral type [5] or local [1][2][3][4].In the former case the idea is to fix at the boundary half of the gravitino potential.On the final surface Σ F one can fix those perturbative modes which multiply harmonics having positive eigenvalues of the intrinsic three-dimensional Dirac operator D of the boundary. On the initial surface one can instead fix those gravitino modes which multiply harmonics having negative eigenvalues of the intrinsic three-dimensional Dirac operator of the boundary. What is non-local in this procedure is the separation of the spectrum of a first-order elliptic operator (our D) into a positive and a negative part. This leads to a sort of positive-and negative-frequency split which is typical for scattering problems [3], but may also be applied to the analysis of quantum amplitudes in finite regions [4].Our paper deals instead with the latter choice, i.e. local boundary conditions for quantum supergravity. By this one usually means a formulation where complementary projection operators act on gravitational and spin-3 2 perturbations. Local boundary conditions of this type were investigated in Refs. [6,7], and then applied to quantum cosmological backgrounds in Refs. [1,4,[8][9][10].