Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New black holes of vacuum Einstein equations with hyperscaling violation
  and Nil geometry horizons   In this paper, we present a new solution of the vacuum Einstein equations in
five dimensions which is a static black hole with hyperscaling violation and
with a three-dimensional horizon modeled by one the eight Thurston geometries,
namely the Nil geometry. This homogeneous geometry is non-trivial in the sense
that it is neither of constant curvature nor a product of constant curvature
manifolds. Using the Hamiltonian formalism, we identify the mass and entropy of
the black hole solution. Curiously enough, in spite of the fact that the
entropy turns to be negative, the mass is positive and the first law of
thermodynamics holds. We also discuss the extension in higher dimension.

21
The categories of this paper are: adap-org
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
6
The categories of this paper are: astro-ph
5
The categories of this paper are: gr-qc