Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Aspects of the Flavour Expansion Theorem   The Flavour Expansion Theorem, which has been recently proposed as a more
general and elegant algebraic method, for the derivation of the commonly used
Mass Insertion Approximation, is revisited. The theorem is reviewed, with
respect to its straightforward applications in Flavour physics, and compared
against the standard diagrammatic flavour basis techniques, in cases where the
latter become inadequate.

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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: adap-org
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: math
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: supr-con
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The categories of this paper are: q-fin
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The categories of this paper are: stat
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The categories of this paper are: econ
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The categories of this paper are: funct-an
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The categories of this paper are: solv-int