Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exact Static Solutions for Scalar Fields Coupled to Gravity in
  $(3+1)$-Dimensions   Einstein's field equations for a spherically symmetric metric coupled to a
massless scalar field are reduced to a system effectively of second order in
time, in terms of the variables $\mu=m/r$ and $y=(\alpha/ra)$, where $a$,
$\alpha$, $r$ and $m$ are as in [W.M. Choptuik, ``Universality and Scaling in
Gravitational Collapse of Massless Scalar Field", \textit{Physical Review
Letters} {\bf{70}} (1993), 9-12]. Solutions for which $\mu $ and $y$ are time
independent may arise either from scalar fields with $\phi_t=0$ or with
$\phi_s=0$ but $\phi$ linear in $t$, called respectively the positive and
negative branches having the Schwarzschild solution characterized by $\phi=0 $
and $\mu_s+\mu=0$ in common. For the positive branch we obtain an exact
solution which have been in fact obtained first in [I.Z. Fisher,``Scalar
mesostatic field with regard for gravitational effects", \textit{Zh. Eksp.
Teor. Fiz.} {\bf{18}} (1948), 636-640, gr-qc/9911008] and rediscovered many
times (see D. Grumiller, ``Quantum dilaton gravity in two dimensions with
matter", PhD thesis, \textit{Technische Universit$\ddot{a}$t, Wien} (2001),
gr-qc/0105078) and we prove that the trivial solution $\mu=0$ is a global
attractor for the region $\mu_s+\mu>0 $, $\mu<1/2$. For the negative branch
discussed first in [M. Wyman, ``Static spherically symmetric scalar fields in
general relativity", \textit{Physical Review D} {\bf{24}} (1981), 839-841]
perturbatively, we prove that $\mu=0$ is a saddle point for the linearized
system, but the non-vacuum solution $\mu=1/4$ is a stable focus and a global
attractor for the region $\mu_s+\mu>0$, $\mu<1/2$.

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The categories of this paper are: cmp-lg
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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: stat
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The categories of this paper are: hep-th
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: cond-mat
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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: astro-ph
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The categories of this paper are: dg-ga
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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: adap-org
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The categories of this paper are: supr-con