We present a simple field-theory model with reduced invariance under diffeomorphisms whose energy-momentum tensor is identical to the sum of pressureless irrotational matter and a cosmological constant. The model action is built from a single scalar field with a canonical kinetic term without any potential or Lagrange multiplier terms. The coupling to gravity is realized through a particular transverse diffeomorphism invariant volume element. The corresponding sound speed is exactly zero in any background geometry, and the model is dynamically identical to $\mathrm{\Lambda }\mathrm{CDM}$. By restoring the full diffeomorphism invariance through the introduction of Stueckelberg-like fields, we obtain an equivalent local scalar-vector theory.

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• Alternative gravity theories
• Dark energy
• Dark matter
• Evolution of the Universe