Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Renormalization Group Approach to Relativistic Cosmology   We discuss the averaging hypothesis tacitly assumed in standard cosmology.
Our approach is implemented in a "3+1" formalism and invokes the coarse
graining arguments, provided and supported by the real-space Renormalization
Group (RG) methods. Block variables are introduced and the recursion relations
written down explicitly enabling us to characterize the corresponding RG flow.
To leading order, the RG flow is provided by the Ricci-Hamilton equations
studied in connection with the geometry of three-manifolds. The properties of
the Ricci-Hamilton flow make it possible to study a critical behaviour of
cosmological models. This criticality is discussed and it is argued that it may
be related to the formation of sheet-like structures in the universe. We
provide an explicit expression for the renormalized Hubble constant and for the
scale dependence of the matter distribution. It is shown that the Hubble
constant is affected by non-trivial scale dependent shear terms, while the
spatial anisotropy of the metric influences significantly the scale-dependence
of the matter distribution.

34
The categories of this paper are: chem-ph
23
The categories of this paper are: solv-int
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
19
The categories of this paper are: eess
35
The categories of this paper are: mtrl-th