Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quasi-degenerate neutrinos in SO(10)   Quark lepton universality inherent in grand unified theories based on
$SO(10)$ gauge group generically leads to hierarchical neutrino masses. We
propose a specific ansatz for the structure of Yukawa matrices in $SO(10)$
models which differ from this generic expectations and lead to quasi degenerate
neutrinos through the type-I seesaw mechanism. Consistency of this ansatz is
demonstrated through a detailed fits to fermion masses and mixing angles all of
which can be explained with reasonable accuracy in a model which uses the Higgs
fields transforming as $10,120$ and $\overline{126}$ representations of
$SO(10)$. The proposed ansatz is shown to follow from an extended model based
on the three generations of the vector like fermions and an $O(3)$ flavour
symmetry. Successful numerical fits are also discussed in earlier proposed
models which used combination of the type-I and type-II seesaw mechanisms for
obtaining quasi degenerate neutrinos. Large neutrino mixing angles emerge as a
consequence of neutrino mass degeneracy in both these cases.

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The categories of this paper are: quant-ph
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The categories of this paper are: atom-ph
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The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
6
The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
4
The categories of this paper are: cond-mat
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The categories of this paper are: nucl-ex
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The categories of this paper are: cs
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The categories of this paper are: math-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: physics
24
The categories of this paper are: dg-ga