Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Signatures of Short Distance Physics in the Cosmic Microwave Background   We systematically investigate the effect of short distance physics on the
spectrum of temperature anistropies in the Cosmic Microwave Background produced
during inflation. We present a general argument-assuming only low energy
locality-that the size of such effects are of order H^2/M^2, where H is the
Hubble parameter during inflation, and M is the scale of the high energy
physics.
  We evaluate the strength of such effects in a number of specific string and M
theory models. In weakly coupled field theory and string theory models, the
effects are far too small to be observed. In phenomenologically attractive
Horava-Witten compactifications, the effects are much larger but still
unobservable. In certain M theory models, for which the fundamental Planck
scale is several orders of magnitude below the conventional scale of grand
unification, the effects may be on the threshold of detectability.
  However, observations of both the scalar and tensor fluctuation contributions
to the Cosmic Microwave Background power spectrum-with a precision near the
cosmic variance limit-are necessary in order to unambiguously demonstrate the
existence of these signatures of high energy physics. This is a formidable
experimental challenge.

8
The categories of this paper are: hep-ex
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
2
The categories of this paper are: math
21
The categories of this paper are: adap-org
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
36
The categories of this paper are: cmp-lg
1
The categories of this paper are: cs
26
The categories of this paper are: bayes-an
10
The categories of this paper are: q-bio