Stealth solutions in mimetic gravity decouple from background dynamics on the lambda=0 branch but impose an infinite hierarchy of constraints on perturbations, rendering the screening limit non-uniform and pathological.
Cosmology in Mimetic SU(2) Gauge Theory
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abstract
It is well known that the standard scalar field mimetic cosmology provides a dark matter-like energy density component. Considering $SU(2)$ gauge symmetry, we study the gauge field extension of the mimetic scenario in spatially flat and curved FLRW spacetimes. Because of the mimetic constraint, the standard Yang-Mills term plays the role of the cosmological constant while the mimetic term provides two different contributions: one is the standard radiation scaling like $ a^{-4}$ while the other contribution in energy density scales as $\propto a^{-2}$. Consequently, in the Friedmann equation we have two different energy densities which scale as $\propto a^{-2}$: one is the mimetic spatial curvature-like and the other is the standard spatial curvature which can compete with each other. The degeneracy between these two contributions are disentangled in this scenario since the mimetic spatial curvature-like term shows up only at the dynamical level while the standard spatial curvature term shows up at both dynamical and kinematical levels.
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UNVERDICTED 2representative citing papers
Higher-derivative extension of dark matter yields an imperfect fluid that matches pressureless dust on homogeneous backgrounds but generates acceleration and vorticity to avoid caustic singularities in inhomogeneous cosmologies.
citing papers explorer
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Fragility of stealth solutions in mimetic gravity
Stealth solutions in mimetic gravity decouple from background dynamics on the lambda=0 branch but impose an infinite hierarchy of constraints on perturbations, rendering the screening limit non-uniform and pathological.
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Imperfect dark matter with higher derivatives
Higher-derivative extension of dark matter yields an imperfect fluid that matches pressureless dust on homogeneous backgrounds but generates acceleration and vorticity to avoid caustic singularities in inhomogeneous cosmologies.