Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: High-temperature expansion of the grand thermodynamic potential for
  scalar particles in crossed electromagnetic fields   The problem of a scalar particle in a constant crossed electromagnetic field
($\mathbf{E}\perp\mathbf{H}$ and $|\mathbf{E}|=|\mathbf{H}|$) is examined. The
high-temperature expansion of the grand thermodynamic potential and vacuum
energy with account for non-perturbative corrections are derived. The
contribution from particles and antiparticles is considered separately. It is
shown that the non-perturbative corrections depend on boundary conditions but
do not depend on fields.

18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
24
The categories of this paper are: dg-ga
20
The categories of this paper are: acc-phys
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
19
The categories of this paper are: eess
4
The categories of this paper are: cond-mat
3
The categories of this paper are: physics
25
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
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph