  Classical higher-derivative gravity is investigated in the context of the
holographic renormalization group (RG). We parametrize the Euclidean time such
that one step of time evolution in (d+1)-dimensional bulk gravity can be
directly interpreted as that of block spin transformation of the d-dimensional
boundary field theory. This parametrization simplifies the analysis of the
holographic RG structure in gravity systems, and conformal fixed points are
always described by AdS geometry. We find that higher-derivative gravity
generically induces extra degrees of freedom which acquire huge mass around
stable fixed points and thus are coupled to highly irrelevant operators at the
boundary. In the particular case of pure R^2-gravity, we show that some region
of the coefficients of curvature-squared terms allows us to have two fixed
points (one is multicritical) which are connected by a kink solution. We
further extend our analysis to Minkowski time to investigate a model of
expanding universe described by the action with curvature-squared terms and
positive cosmological constant, and show that, in any dimensionality but four,
one can have a classical solution which describes time evolution from a de
Sitter geometry to another de Sitter geometry, along which the Hubble parameter
changes drastically.

High Energy Physics - Theory