Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The low energy effective theory and nucleon stability   We show that the Standard Model Lagrangian, including small neutrino masses,
has an anomaly-free discrete Z_6 symmetry. Anomaly cancellation requires the
number of family to be 3 mod 6. This symmetry can ensure the stability of the
nucleon even when the threshold of new physics \Lambda is low as 10^2 GeV. All
\Delta B=1 and \Delta B=2 (B is the baryon number) effective operators are
forbidden by the Z_6 symmetry. \Delta B=3 operators are allowed, but they arise
only at dimension 15. We suggest a simple mechanism for realizing reasonable
neutrino masses and mixings even with such a low scale for \Lambda.

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The categories of this paper are: atom-ph
14
The categories of this paper are: math-ph
2
The categories of this paper are: math
16
The categories of this paper are: stat
15
The categories of this paper are: nucl-ex
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The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
36
The categories of this paper are: cmp-lg
3
The categories of this paper are: physics
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys