Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Two Double String Theory Actions: Non-Covariance vs. Covariance   The aim of this work is to achieve a formulation of the bosonic string theory
in which T-duality appears as a manifest symmetry. Two models exhibiting this
property are discussed. The first is based on the stringy extension of the
Floreanini-Jackiw Lagrangians for chiral fields and is characterized by the
loss of manifest covariance on the world-sheet, recovered on mass-shell. The
second model exhibits two-dimensional covariance while doubling a priori the
string coordinates in the target space. They are shown to be equivalent.

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The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
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The categories of this paper are: nucl-ex
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The categories of this paper are: nucl-th
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The categories of this paper are: plasm-ph
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The categories of this paper are: adap-org
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-lat
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The categories of this paper are: cs
34
The categories of this paper are: chem-ph
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The categories of this paper are: stat
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The categories of this paper are: q-bio
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The categories of this paper are: astro-ph
27
The categories of this paper are: comp-gas