Massless Limit of Gravitational Higgs Mechanism

Understand

In gravitational Higgs mechanism graviton components acquire mass via spontaneous diffeomorphism breaking by scalar vacuum expectation values.

• We point out that in the massless limit the resulting theory is not Einstein-Hilbert gravity (EHG) but constrained gravity (CG).
• Consequently, massive solutions in the massless limit must be compared to those in CG (as opposed to EHG).
• We discuss spherically symmetric solutions in this context.