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In massive gravity and in bimetric theories of gravity, two constraints areneeded to eliminate the two phase-space degrees of freedom of theBoulware-Deser ghost. For recently proposed non-linear theories, a Hamiltonianconstraint has been shown to exist and an associated secondary constraint wasargued to arise as well. In this paper we explicitly demonstrate the existenceof the secondary constraint. Thus the Boulware-Deser ghost is completely absentfrom these non-linear massive gravity theories and from the correspondingbimetric theories.

Confirmation of the Secondary Constraint and Absence of Ghost in Massive Gravity and Bimetric Gravity