Energy and supercharge in higher derivative gravity

Abstract

Explicit energy expressions are derived, by supergravity embedding, for quadratic curvature actions with or without Einstein terms. Applications include existence of stability domains in R+R^2 models, vanishing of supercharge in conformal supergravity and indefiniteness of the energy in the generic case. The contradiction between the indefiniteness of the energy and its seemingly positive supersymmetric H=ΣQ_α^2 form is traced to the necessarily indefinite Hilbert space of the fermionic sector, which implies H is really a difference of squares.

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