Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Electromagnetism and perfect fluids interplay in multidimensional
  spacetimes   We consider fields in (D>2)-dimensional spacetime, whose potential is r-form
(skew-symmetric tensor of rank r), the field tensor F being its exterior
derivative and the Lagrangian, a function of the quadratic invariant I of this
tensor. It is shown that vector field (r=1) describes electromagnetic field
only for D=4. In particular, for D=3 and the Lagrangean L as any function of
the above-mentioned invariant, the (r=1)-field has energy-momentum tensor
identical with that of a perfect fluid whose equation of state depends on the
choice of L(I).

4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
21
The categories of this paper are: adap-org
14
The categories of this paper are: math-ph
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom
23
The categories of this paper are: solv-int
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex