Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quintessence with quadratic coupling to dark matter   We introduce a new form of coupling between dark energy and dark matter that
is quadratic in their energy densities. Then we investigate the background
dynamics when dark energy is in the form of exponential quintessence. The three
types of quadratic coupling all admit late-time accelerating critical points,
but these are not scaling solutions. We also show that two types of coupling
allow for a suitable matter era at early times and acceleration at late times,
while the third type of coupling does not admit a suitable matter era.

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The categories of this paper are: hep-ph
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
9
The categories of this paper are: nlin
11
The categories of this paper are: hep-lat
30
The categories of this paper are: q-alg
34
The categories of this paper are: chem-ph
7
The categories of this paper are: hep-th
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
27
The categories of this paper are: comp-gas