Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Energy-momentum relation for solitary waves of relativistic wave
  equations   Solitary waves of relativistic invariant nonlinear wave equation with
symmetry group U(1) are considered. We prove that the energy-momentum relation
for spherically symmetric solitary waves coincides with the Einstein
energy-momentum relation for point particles.

3
The categories of this paper are: physics
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
10
The categories of this paper are: q-bio
16
The categories of this paper are: stat
19
The categories of this paper are: eess
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
36
The categories of this paper are: cmp-lg
12
The categories of this paper are: nucl-th
21
The categories of this paper are: adap-org
33
The categories of this paper are: plasm-ph
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an