Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Compactified Picard stacks over $\bar{\mathcal M}_g$   We study algebraic (Artin) stacks over $\bar{\mathcal M}_g$ giving a
functorial way of compactifying the relative degree $d$ Picard variety for
families of stable curves. We also describe for every $d$ the locus of genus
$g$ stable curves over which we get Deligne-Mumford stacks strongly
representable over $\bar{\mathcal M}_g$.

23
The categories of this paper are: solv-int
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The categories of this paper are: nucl-ex
28
The categories of this paper are: alg-geom
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The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
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The categories of this paper are: supr-con
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The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
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The categories of this paper are: econ
5
The categories of this paper are: gr-qc
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The categories of this paper are: hep-th
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The categories of this paper are: math-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: stat
6
The categories of this paper are: astro-ph
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The categories of this paper are: q-fin