Consistency between black hole and mimetic gravity -- Case of $(2+1)$-dimensional gravity

Understand

We show that the mimetic theory with the constraint $g^{\rho \sigma}\partial_\rho\phi \partial_\sigma\phi=1$ cannot realize the black hole geometry with the horizon(s).

• To overcome such issue, we may change the mimetic constraint a little bit by $\omega(\phi) g^{\rho \sigma}\partial_\rho\phi \partial_\sigma\phi=-1,$ where $\omega(\phi)$ is a function of the scalar field $\phi$.
• As an example, we consider $(2+1)$-dimensional mimetic gravity with the mimetic potential and construct black hole (BH) solutions by using this modified constraint.
• We study three different classes: In the first class, we assume the Lagrange multiplier and mimetic potential are vanishing and obtain a BH solution that fully matches the BH of GR despite the non-triviality of the mimetic field which ensures the study presented in {\it JCAP 01 (2019) 058}.