Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Static spacetimes haunted by a phantom scalar field II: dilatonic
  charged solutions   We present a method to generate static solutions in the Einstein-Maxwell
system with a (phantom) dilaton field in $n(\ge 4)$-dimensions, based upon the
symmetry of the target space for the nonlinear sigma model. Unlike the
conventional Einstein-Maxwell-dilaton system, there appears a critical value of
the coupling constant for a phantom dilaton field. In the noncritical case, the
target space is $\mathbb R\times {\rm SL}(2,\mathbb R)/H$ with the maximal
subgroup $H=\{{\rm SO}(2), {\rm SO}(1,1)\}$, whereas in the critical case the
target space becomes a symmetric pp-wave and the corresponding Killing vectors
form a non-semisimple algebra. In either case, we apply the formalism to charge
up the neutral solutions and show the analytical expression for dilatonic
charged versions of (i) the Fisher solution, (ii) the Gibbons solution, and
(iii) the Ellis-Bronnikov solution. We discuss global structures of these
solutions in detail. It turns out that some solutions contained in the Fisher
and Gibbons classes possess the parallelly propagated (p.p) curvature
singularities in the parameter region where all the scalar curvature invariants
remain bounded. These p.p curvature singularities are not veiled by a horizon,
thrusting them into physically untenable nakedly singular spacetimes. We also
demonstrate that the dilatonic-charged Ellis-Bronnikov solution admits a
parameter range under which the solution represents a regular wormhole
spacetime in the two-sided asymptotically flat regions.

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The categories of this paper are: nucl-th
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The categories of this paper are: funct-an
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The categories of this paper are: econ
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The categories of this paper are: q-alg
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The categories of this paper are: hep-ph
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The categories of this paper are: eess
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The categories of this paper are: hep-ex
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The categories of this paper are: alg-geom
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The categories of this paper are: astro-ph
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The categories of this paper are: math-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-fin
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The categories of this paper are: math
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The categories of this paper are: cmp-lg
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-lat