Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Standard Model and New Physics contributions to $K_L$ and $K_S$ into
  four leptons   We study the $K_L$ and $K_S$ decays into four leptons ($e\bar{e}e\bar{e}, \,
\mu\bar{\mu}\mu\bar{\mu},\, e\bar{e}\mu\bar{\mu}$) where we use a form factor
motivated by vector meson dominance, and show the dependence of the branching
ratios and spectra from the slopes. A precise determination of short distance
contribution to $K_L\to \mu\mu$ is affected by our ignorance on the sign of the
amplitude $\mathcal{A}(K_L\to \gamma\gamma)$ but we show a possibility to
measure the sign of this amplitude by studying $K_L$ and $K_S$ decays in four
leptons. We also investigate the effect of New Physics contributions for these
decays.

10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
6
The categories of this paper are: astro-ph
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
3
The categories of this paper are: physics
25
The categories of this paper are: patt-sol
16
The categories of this paper are: stat
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom