Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dynamical symmetry restoration for a higher-derivative four-fermion
  model in an external electromagnetic field   A four-fermion model with additional higher-derivative terms is investigated
in an external electromagnetic field. The effective potential in the leading
order of large-N expansion is calculated in external constant magnetic and
electric fields.
  It is shown that, in contrast to the former results concerning the universal
character of "magnetic catalysis" in dynamical symmetry breaking, in the
present higher-derivative model the magnetic field restores chiral symmetry
broken initially on the tree level. Numerical results describing a second-order
phase transition that accompanies the symmetry restoration at the quantum level
are presented.

14
The categories of this paper are: math-ph
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
17
The categories of this paper are: q-fin
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
30
The categories of this paper are: q-alg
10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys