Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Cosmologies in Horndeski's second-order vector-tensor theory   Horndeski derived a most general vector-tensor theory in which the vector
field respects the gauge symmetry and the resulting dynamical equations are of
second order. The action contains only one free parameter, $\lambda$, that
determines the strength of the non-minimal coupling between the gauge field and
gravity. We investigate the cosmological consequences of this action and
discuss observational constraints. For $\lambda<0$ we identify singularities
where the deceleration parameter diverges within a finite proper time. This
effectively rules out any sensible cosmological application of the theory for a
negative non-minimal coupling. We also find a range of parameter that gives a
viable cosmology and study the phenomenology for this case. Observational
constraints on the value of the coupling are rather weak since the interaction
is higher-order in space-time curvature.

1
The categories of this paper are: cs
19
The categories of this paper are: eess
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph