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Viscosity of holographic fluid in the presence of dark matter sector

Based on the gauge/gravity correspondence, the hydrodynamic response coefficients, shear and Hall viscosities, have been studied. The holographic model of Einstein-Maxwell- AdS $(3+1)$-dimensional system additionally coupled with the another gauge field mimicking the {\it dark matter} sector, as well as, gravitational Chern-Simons term bounded with a dynamical scalar field, were taken into account. Condensation of the scalar field provides the parity violating term. Both shear and Hall viscosities have been calculated and their dependence on $α$ - the coupling constant between matter and {\it dark matter} sectors has been studied. To the lowest order in the derivative expansion and perturbation in $α$, the shear viscosity is not influenced by the {\it dark matter}, while the Hall component linearly depends on $α$.