Spontaneous symmetry breaking and gravity

Understand

Gravity is usually considered to be irrelevant as far as the physics of elementary particles is concerned and, in particular, in the context of the spontaneous symmetry breaking (SSB) mechanism.

• We describe a version of the SSB mechanism in which gravity plays a direct role.
• We work in the context of diffeomorphism invariant gauge theories, which exist for any non-abelian gauge group G, and which have second order in derivatives field equations.
• We show that any (non-trivial) vacuum solution of such a theory gives rise to an embedding of the group SU(2) into G, and thus breaks G down to SU(2) times its centralizer in G.