Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Circular Polarization of Primordial Gravitational Waves in
  String-inspired Inflationary Cosmology   We study a mechanism to produce the circular polarization of primordial
gravitational waves.
  The circular polarization is generated during the super-inflation driven by
the Gauss-Bonnet term in the string-inspired cosmology. The instability in the
tensor mode caused by the Gauss-Bonnet term and the parity violation due to the
gravitational Chern-Simons term are the essential ingredients of the mechanism.
We also discuss detectability of the produced circular polarization of
gravitational waves. It turns out that the simple model of single-field
inflation contradicts CMB observations. To circumvent this difficulty, we
propose a two-field inflation model. In this two-field model, the circular
polarization of gravitational waves is created in the frequency range designed
by the Big-Bang Observer (BBO) or the deci-hertz gravitational-wave observatory
(DECIGO).

25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
12
The categories of this paper are: nucl-th
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
16
The categories of this paper are: stat
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The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
4
The categories of this paper are: cond-mat
18
The categories of this paper are: econ
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat