Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Suppressing the impact of a high tensor-to-scalar ratio on the
  temperature anisotropies   The BICEP2 collaboration has reported a strong B mode signal in the CMB
polarization, which is well fit by a tensor-to-scalar ratio of r ~ 0.2. This is
greater than the upper limit r < 0.11 obtained from the temperature
anisotropies under the assumption of a constant scalar spectral index n_s. This
discrepancy can be reduced once the statistical error and the contamination
from polarized dust are accounted for. If however a large value for r will be
confirmed, it will need to be reconciled with the temperature anisotropies
data. The most advocated explanation involves a variation of n_s with scales
(denoted as running) that has a magnitude significantly greater than the
generic slow roll predictions. We instead study the possibility that the large
scale temperature anisotropies are not enhanced because of a suppression of the
scalar power at large scales. Such a situation can be achieved for instance by
a sudden change of the speed of the inflaton (by about 14 %), and we show that
it fits the temperature anisotropies and polarization data considerably better
than a constant running (its chi^2 improves by ~ 7.5 over that of the constant
running, at the cost of one more parameter). We also consider the possibility
that the large scale temperature fluctuations are suppressed by an
anti-correlation between tensor and scalar modes. Unfortunately, while such
effect does affect the temperature fluctuations at large scales, it does not
affect the temperature power spectrum and cannot, therefore, help in
reconciling a large value of r with the limits from temperature fluctuations.

18
The categories of this paper are: econ
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
30
The categories of this paper are: q-alg
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat