Dilaton

In particle physics, the dilaton is a hypothetical particle that appears in theories with extra dimensions when the volume of the compactified dimensions is allowed to vary. It appears for instance in Kaluza–Klein theory's compactifications of extra dimensions. It is a particle of a scalar field Φ, a scalar field that always comes with gravity. For comparison, in standard general relativity, Newton's constant, or equivalently the Planck mass is a constant. If this constant is promoted to a dynamical field, the result is the dilaton.