Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The rare K-decays and $Z^0$-penguin contributions in the
  Topcolor-assisted technicolor models   We calculate the new contributions to the rare decays $K^+ \to \pi^+ \nu \bar
\nu$, $K_L \to \pi^0 \nu \bar \nu$ and $K_L \to \mu^+ \mu^-$ from new
$Z^0$-penguin and box diagrams induced by the unit-charged scalars
$(\tilde{\pi}^\pm, \tilde{H}^\pm, \pi_1^\pm, \pi_8^\pm)$ appeared in the
Topcolor-assisted technicolor (TC2) models. We find that: (a) the unit-charged
top-pion $\tilde{\pi}^\pm$ and b-pion $\tilde{H}^\pm$ can provide large
contributions to the rare K-decays if they are relatively light; (b) the size
of mixing elements $D_{L,R}^{ij}$ ($i \neq j$) is strongly constrained by the
data of $B^0$ meson mixing: $|a_R^{ts}|, |a_R^{td}| < 0.01$ for
$a_L^{td}=a_L^{ts}=1/2$ and $m_{\tilde{H}^0}\leq 600GeV$; (c) the enhancements
to the branching ratios of rare K-decays from new scalars can be as large as
one order of magnitude; (d) there is a strong cancellation between the short-
and long-distance dispersive part of the decay $K_L \to \mu^+ \mu^-$, the
constraint on the new short-distance part from this decay mode is thus not
strong; (e) the typical TC2 model under study is generally consistent with the
available rare K-decay data.

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The categories of this paper are: econ
35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
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The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
4
The categories of this paper are: cond-mat
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The categories of this paper are: atom-ph
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The categories of this paper are: q-fin
7
The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol