Dark matter as a ghost free conformal extension of Einstein theory

Understand

We discuss ghost free models of the recently suggested mimetic dark matter theory.

• This theory is shown to be a conformal extension of Einstein general relativity.
• Dark matter originates from gauging out its local Weyl invariance as an extra degree of freedom which describes a potential flow of the pressureless perfect fluid.
• For a positive energy density of this fluid the theory is free of ghost instabilities, which gives strong preference to stable configurations with a positive scalar curvature and trace of the matter stress tensor.