Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Metastring Theory and Modular Space-time   String theory is canonically accompanied with a space-time interpretation
which determines S-matrix-like observables, and connects to the standard
physics at low energies in the guise of local effective field theory. Recently,
we have introduced a reformulation of string theory which does not rely on an
{\it a priori} space-time interpretation or a pre-assumption of locality. This
\hlt{metastring theory} is formulated in such a way that stringy symmetries
(such as T-duality) are realized linearly. In this paper, we study metastring
theory on a flat background and develop a variety of technical and
interpretational ideas. These include a formulation of the moduli space of
Lorentzian worldsheets, a careful study of the symplectic structure and
consequently consistent closed and open boundary conditions, and the string
spectrum and operator algebra. What emerges from these studies is a new quantum
notion of space-time that we refer to as a quantum Lagrangian or equivalently a
\hlt{modular space-time}. This concept embodies the standard tenets of quantum
theory and implements in a precise way a notion of {relative locality}. The
usual string backgrounds (non-compact space-time along with some toroidally
compactified spatial directions) are obtained from modular space-time by a
limiting procedure that can be thought of as a correspondence limit.

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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-ex
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The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: eess
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: ao-sci
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The categories of this paper are: hep-lat
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The categories of this paper are: adap-org
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The categories of this paper are: cs
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The categories of this paper are: math
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The categories of this paper are: q-fin
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The categories of this paper are: econ
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The categories of this paper are: supr-con
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The categories of this paper are: solv-int