Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravity waves goodbye   The detection of a stochastic background of long-wavelength gravitational
waves (tensors) in the cosmic microwave background (CMB) anisotropy would be an
invaluable probe of the high energy physics of the early universe.
Unfortunately a combination of factors now makes such a detection seem
unlikely: the vast majority of the CMB signal appears to come from density
perturbations (scalars) - detailed fits to current observations indicate a
tensor-to-scalar quadrupole ratio of T/S < 0.5 for the simplest models; and on
the theoretical side the best-motivated inflationary models seem to require
very small T/S. Unfortunately CMB temperature anisotropies can only probe a
gravity wave signal down to T/S \sim 10% and optimistic assumptions about
polarization of the CMB only lower this another order of magnitude.

20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th
9
The categories of this paper are: nlin
13
The categories of this paper are: quant-ph
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
27
The categories of this paper are: comp-gas
18
The categories of this paper are: econ
8
The categories of this paper are: hep-ex
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph