Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Uniqueness of M-theory PP-Wave Background with Extra Supersymmetries   We examine Killing spinor equations of the general eleven-dimensional pp-wave
backgrounds, which contain a scalar H(x^m,x^-) in the metric and a three-form
\xi(x^m,x^-) in the flux. Considering non-harmonic extra Killing spinors, we
show that if the backgrounds admit at least one extra Killing spinor in
addition to the standard 16 Killing spinors, they can be reduced to the form
with H=A_{mn}(x^-)x^mx^n and \xi(x^-) modulo coordinate transformations. We
further examine the cases in which the extra Killing spinor is characterized by
a set of Cartan matrices. The super-isometry algebras of the resulting
backgrounds are also derived.

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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: dg-ga
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The categories of this paper are: plasm-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ph
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The categories of this paper are: funct-an
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The categories of this paper are: supr-con
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The categories of this paper are: acc-phys
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The categories of this paper are: q-bio
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: quant-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: atom-ph