Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: BICEP2 I: Detection Of B-mode Polarization at Degree Angular Scales   (abridged for arXiv) We report results from the BICEP2 experiment, a cosmic
microwave background (CMB) polarimeter specifically designed to search for the
signal of inflationary gravitational waves in the B-mode power spectrum around
$\ell\sim80$. The telescope comprised a 26 cm aperture all-cold refracting
optical system equipped with a focal plane of 512 antenna coupled transition
edge sensor 150 GHz bolometers each with temperature sensitivity of
$\approx300\mu\mathrm{K}_\mathrm{CMB}\sqrt{s}$. BICEP2 observed from the South
Pole for three seasons from 2010 to 2012. A low-foreground region of sky with
an effective area of 380 square deg was observed to a depth of 87 nK deg in
Stokes $Q$ and $U$. We find an excess of $B$-mode power over the base
lensed-LCDM expectation in the range $30< \ell< 150$, inconsistent with the
null hypothesis at a significance of $> 5\sigma$. Through jackknife tests and
simulations we show that systematic contamination is much smaller than the
observed excess. We also examine a number of available models of polarized dust
emission and find that at their default parameter values they predict power
$\sim(5-10)\times$ smaller than the observed excess signal. However, these
models are not sufficiently constrained to exclude the possibility of dust
emission bright enough to explain the entire excess signal. Cross correlating
BICEP2 against 100 GHz maps from the BICEP1 experiment, the excess signal is
confirmed and its spectral index is found to be consistent with that of the
CMB, disfavoring dust at $1.7\sigma$. The observed $B$-mode power spectrum is
well fit by a lensed-LCDM + tensor theoretical model with tensor-to-scalar
ratio $r=0.20^{+0.07}_{-0.05}$, with $r=0$ disfavored at $7.0\sigma$.
Accounting for the contribution of foreground dust will shift this value
downward by an amount which will be better constrained with upcoming data sets.

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The categories of this paper are: stat
27
The categories of this paper are: comp-gas
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The categories of this paper are: nucl-ex
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The categories of this paper are: solv-int
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The categories of this paper are: cs
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The categories of this paper are: hep-ex
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The categories of this paper are: chem-ph
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The categories of this paper are: math-ph
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom
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The categories of this paper are: nlin
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The categories of this paper are: econ
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The categories of this paper are: chao-dyn
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The categories of this paper are: physics
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The categories of this paper are: ao-sci
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The categories of this paper are: q-fin