Topological excitations are certain features of classical solutions of gauge field theories.
Namely, a gauge field theory on a manifold
M
with a gauge group
G
may possess classical solutions with a (quantized) topological invariant called topological charge. The term topological excitation especially refers to a situation when the topological charge is an integral of a localized quantity.
Examples:
1)
M
=
R
2
,
G
=
U
(
1
)
, the topological charge is called magnetic flux.
2)
M
=
R
3
,
G
=
S
O
(
3
)
/
U
(
1
)
, the topological charge is called magnetic charge.
The concept of a topological excitation is almost synonymous with that of a topological defect.
