Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Closed superstrings in magnetic field: instabilities and supersymmetry
  breaking   We consider a 2-parameter class of solvable closed superstring models which
`interpolate' between Kaluza-Klein and dilatonic Melvin magnetic flux tube
backgrounds. The spectrum of string states has similarities with Landau
spectrum for a charged particle in a uniform magnetic field. The presence of
spin-dependent `gyromagnetic' interaction implies breaking of supersymmetry and
possible existence (for certain values of magnetic parameters) of tachyonic
instabilities. We study in detail the simplest example of the Kaluza-Klein
Melvin model describing a superstring moving in flat but non-trivial 10-d space
containing a 3-d factor which is a `twisted' product of a 2-plane and an
internal circle. We also discuss the compact version of this model constructed
by `twisting' the product of the two groups in SU(2) x U(1) WZNW theory without
changing the local geometry (and thus the central charge). We explain how the
supersymmetry is broken by continuous `magnetic' twist parameters and comment
on possible implications for internal space compactification models.
(Contribution to the Proceedings of the 1995 Erice School "String Gravity and
Physics at the Planck Scale")

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The categories of this paper are: alg-geom
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The categories of this paper are: hep-lat
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The categories of this paper are: stat
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The categories of this paper are: nucl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: chao-dyn
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The categories of this paper are: hep-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: math
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The categories of this paper are: eess
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The categories of this paper are: funct-an
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The categories of this paper are: dg-ga
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The categories of this paper are: comp-gas
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The categories of this paper are: quant-ph