Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Interacting holographic dark energy   We demonstrate that a transition from decelerated to accelerated cosmic
expansion arises as a pure interaction phenomenon if pressureless dark matter
is coupled to holographic dark energy whose infrared cutoff scale is set by the
Hubble length. In a spatially flat universe the ratio of the energy densities
of both components remains constant through this transition, while it is
subject to slow variations for non-zero spatial curvature. The coincidence
problem is dynamized and reformulated in terms of the interaction rate. An
early matter era is recovered since for negligible interaction at high
redshifts the dark energy itself behaves as matter. A simple model for this
dynamics is shown to fit the SN Ia data. The constant background energy density
ratio simplifies the perturbation analysis which is characterized by
non-adiabatic features.

35
The categories of this paper are: mtrl-th
16
The categories of this paper are: stat
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
22
The categories of this paper are: chao-dyn
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
4
The categories of this paper are: cond-mat
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math
19
The categories of this paper are: eess
3
The categories of this paper are: physics