Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Axion Model with Intermediate Scale Fermionic Dark Matter   We investigate a non-supersymmetric $SO(10)\times U(1)_{\rm PQ}$ axion model
in which the spontaneous breaking of $U(1)_{\rm PQ}$ occurs after inflation,
and the axion domain wall problem is resolved by employing the Lazarides-Shafi
mechanism. This requires the introduction of two fermion 10-plets, such that
the surviving discrete symmetry from the explicit $U(1)_{\rm PQ}$ breaking by
QCD instantons is reduced from $Z_{12}$ to $Z_4$, where $Z_4$ coincides with
the center of $SO(10)$ (more precisely $Spin(10)$). An unbroken $Z_2$ subgroup
of $Z_4$ yields intermediate scale topologically stable strings, as well as a
stable electroweak doublet non-thermal dark matter candidate from the fermion
10-plets with mass comparable to or somewhat smaller than the axion decay
constant $f_{\rm a}$. We present an explicit realization with inflation taken
into account and which also incorporates non-thermal leptogenesis. The fermion
dark matter mass lies in the $3\times 10^{8}-10^{10}~{\rm GeV}$ range and its
contribution to the relic dark matter abundance can be comparable to that from
the axion.

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The categories of this paper are: hep-th
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The categories of this paper are: gr-qc
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
18
The categories of this paper are: econ
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
2
The categories of this paper are: math