Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: QCD with two flavors of Wilson fermions: The QCD vacuum, the Aoki vacuum
  and other vacua   We discuss the vacuum structure of QCD with two flavors of Wilson fermions.
We derive two possible scenarios: (i) If the spectral density
$\rho_U(\lambda,\kappa)$ of the overlap hamiltonian in a fixed background gauge
field is not symmetric in $\lambda$, Hermiticity is violated and Hermiticity
violation effects could influence numerical determinations of the $\eta$ meson
mass if we are not near enough to the continuum limit, where Hermiticity should
be recovered; (ii) otherwise we argue that, under certain assumptions, new
phases appear beside the Aoki phase, which can be characterized by a
nonvanishing vacuum expectation value of
$i\bar\psi_u\gamma_5\psi_u+i\bar\psi_d\gamma_5\psi_d$, and with vacuum states
that cannot be connected with the Aoki vacua by parity-flavor symmetry
transformations. Quenched numerical simulations suggest that the second
scenario is more likely realized.

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The categories of this paper are: q-alg
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: adap-org
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The categories of this paper are: chem-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
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The categories of this paper are: alg-geom
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-fin
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The categories of this paper are: stat
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The categories of this paper are: patt-sol
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The categories of this paper are: funct-an
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The categories of this paper are: nlin