Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Zel'dovich states with very small mass and charge in nonlinear
  electrodynamics coupled to gravity   It is shown that in non-linear electrodynamics (in particular, Born-Infeld
one) in the framework of general relativity there exist "weakly singular"
configurations such that (i) the proper mass M is finite in spite of
divergences of the energy density, (ii) the electric charge q and Schwarzschild
mass m ~ q can be made as small as one likes, (iv) all field and energy
distributions are concentrated in the core region. This region has an almost
zero surface area but a finite longitudinal size L=2M. Such configurations can
be viewed as a new version of a classical analogue of an elementary particle.

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The categories of this paper are: patt-sol
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
31
The categories of this paper are: ao-sci
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg