Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Selection Rules for Nonrenormalizable Couplings in Superstring Theories   We study nonrenormalizable coupling terms in $Z_N$ orbifold models.
Nontrivial selection rules of couplings are provided and cannot be understood
in terms of a simple symmetry of effective field theories. We also discuss
phenomenological implications of theses selection rules for the quark mass
matrices.

2
The categories of this paper are: math
10
The categories of this paper are: q-bio
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The categories of this paper are: q-fin
13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
9
The categories of this paper are: nlin
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The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
22
The categories of this paper are: chao-dyn
37
The categories of this paper are: supr-con
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The categories of this paper are: gr-qc
6
The categories of this paper are: astro-ph