Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Finite-time future singularities models in $f(T)$ gravity and the
  effects of viscosity   We investigate models of future finite-time singularities in $f(T)$ theory,
where $T$ is the torsion scalar. The algebraic function $f(T)$ is put as the
teleparallel term $T$ plus an arbitrary function $g(T)$. A suitable expression
of the Hubble parameter is assumed and constraints are imposed in order to
provide an expanding universe. Two parameters $\beta$ and $H_s$ that appear in
the Hubble parameter are relevant in specifying the types of singularities.
Differential equations of $g(T)$ are established and solved, leading to the
algebraic $f(T)$ models for each type of future finite time singularity.
Moreover, we take into account the viscosity in the fluid and discuss three
interesting cases: constant viscosity, viscosity proportional to $\sqrt{-T}$
and the general one where the viscosity is proportional to $(-T)^{n/2}$, where
$n$ is a natural number. We see that for the first and second cases, in
general, the singularities are robust against the viscous fluid, while for the
general case, the Big Rip and the Big Freeze can be avoided from the effects of
the viscosity for some values of $n$.

15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas