Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Neutrino masses in the $SU(4)_L \otimes U(1)_X$ electroweak extension of
  the standard model   We study the neutrino mass generation in the $SU(4)_L \otimes U(1)_X$
electroweak extension of the standard model by considering non-renormalizable
dimension five effective operators. It is shown that there exist two topologies
for the realizations of such an operator at the tree-level and for one of the
three-family models is explore the neutrino phenomenology after extending its
particle content with an $SU(4)_L$ fermion singlet and a scalar decuplet.
Constraints in the available parameters space of the model are partially
discussed.

16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
28
The categories of this paper are: alg-geom
5
The categories of this paper are: gr-qc
8
The categories of this paper are: hep-ex
33
The categories of this paper are: plasm-ph
24
The categories of this paper are: dg-ga
29
The categories of this paper are: funct-an