Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum effects, soft singularities and the fate of the universe in a
  braneworld cosmology   We examine a class of braneworld models in which the expanding universe
encounters a "quiescent" future singularity. At a quiescent singularity, the
energy density and pressure of the cosmic fluid as well as the Hubble parameter
remain finite while all derivatives of the Hubble parameter diverge (i.e.,
${\dot H}$, ${\ddot H}$, etc. $\to \infty$). Since the Kretschmann invariant
diverges ($R_{iklm}R^{iklm} \to \infty$) at the singularity, one expects
quantum effects to play an important role as the quiescent singularity is
approached. We explore the effects of vacuum polarization due to massless
conformally coupled fields near the singularity and show that these can either
cause the universe to recollapse or, else, lead to a softer singularity at
which $H$, ${\dot H}$, and ${\ddot H}$ remain finite while ${\dddot H}$ and
higher derivatives of the Hubble parameter diverge. An important aspect of the
quiescent singularity is that it is encountered in regions of low density,
which has obvious implications for a universe consisting of a cosmic web of
high and low density regions -- superclusters and voids. In addition to vacuum
polarization, the effects of quantum particle production of non-conformal
fields are also likely to be important. A preliminary examination shows that
intense particle production can lead to an accelerating universe whose Hubble
parameter shows oscillations about a constant value.

1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
18
The categories of this paper are: econ
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
17
The categories of this paper are: q-fin
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol