Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Lepton-number violating meson decays in theories beyond the Standard
  Model   After discussion of mechanisms of lepton number violation, we consider meson
decays $K^+ \to\pi^ - \ell ^ + \ell '^ +$ and $D^ + \to K^ - \ell ^ + \ell '^
+$ ($\ell,\ell ' = e,\mu $) with $\Delta L= 2$ in the Standard Model extended
by massive Majorana neutrinos and in a supersymmetric extension of the Standard
Model with explicit breaking of R-parity by trilinear or bilinear Yukawa
couplings in the superpotential. We give estimates of the branching ratios for
these decays and compare the effectiveness of various decay mechanisms taking
into account present experimental bounds on lepton mixing, masses of neutrinos
and superparticles, and R-parity violating couplings.

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
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
15
The categories of this paper are: nucl-ex
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
30
The categories of this paper are: q-alg
1
The categories of this paper are: cs
22
The categories of this paper are: chao-dyn
11
The categories of this paper are: hep-lat
13
The categories of this paper are: quant-ph
21
The categories of this paper are: adap-org