Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Monopoles, Axions and Intermediate Mass Dark Matter   We present a solution to the cosmological problem encountered in
(supersymmetric) grand unified theories due to copious monopole production at
the end of hybrid inflation. By employing thermal inflation ``driven'' by the
U(1) axion symmetry, the superheavy monopole flux can be naturally suppressed
to values that should be accessible to dedicated large scale experiments. The
U(1) axion symmetry also helps generate the right magnitude for the mu term of
the minimal supersymmetric standard model. An important by-product is the
predicted existence of stable or very long-living fermions possessing
intermediate scale masses of order 10^{12} GeV. Their presence is required for
implementing thermal inflation, and their stability is due to a Z_2 symmetry.
They may constitute a sizable fraction of cold dark matter, and possibly help
explain the ultra-high energy cosmic ray events. The rest of cold dark matter
may consist of axions. Although our discussion is carried out within the
framework of supersymmetric SU(4)_c x SU(2)_L x SU(2)_R, it can be extended to
other grand unified gauge groups such as SU(3)_c x SU(3)_L x SU(3)_R or SO(10).

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The categories of this paper are: astro-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: funct-an
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The categories of this paper are: hep-th
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The categories of this paper are: math
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The categories of this paper are: alg-geom
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-ex
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: q-bio
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The categories of this paper are: bayes-an
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The categories of this paper are: plasm-ph
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The categories of this paper are: gr-qc