Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dark Energy Models in the w - w' Plane   We examine the behavior of dark energy models in the plane defined by w (the
equation of state parameter for the dark energy) and w' (the derivative of w
with respect to the logarithm of the scale factor). For non-phantom barotropic
fluids with positive squared sound speed, we find that w' < 3w(w+1), the
opposite of the bound on quintessence models previously derived by Caldwell and
Linder. Thus, these barotropic models and quintessence models for the dark
energy occupy disjoint regions in the w - w' plane. We also derive two new
bounds for quintessence models in the w - w' plane: the first is a general
bound for any scalar field with a monotonic potential, while the second
improves on the Caldwell-Linder bound for tracker quintessence models.
Observationally distinguishing barotropic models from quintessence models
requires \sigma(w') < 1+w.

20
The categories of this paper are: acc-phys
26
The categories of this paper are: bayes-an
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci