Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Four-fermion Interaction Model in a Constant Magnetic Field at Finite
  Temperature and Chemical Potential   We investigate an influence of an external magnetic field on chiral symmetry
breaking in a four-fermion interaction model at finite temperature and chemical
potential. By using the Fock-Schwinger proper-time method, we calculate the
effective potential for the four-fermion interaction model at the leading order
of the $1/N_c$ expansion. A phase structure of the chiral symmetry breaking is
shown on $T$-$\mu$, $H$-$T$ and $\mu$-$H$ planes. The external magnetic field
modifies the phase structure. It is found that a new phase appears for a large
chemical potential.

11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
26
The categories of this paper are: bayes-an
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
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The categories of this paper are: acc-phys
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
18
The categories of this paper are: econ