We construct static and time dependent exact soliton solutions for a theory of scalar
fields taking values on a wide class of two dimensional target spaces, and defined
on the four dimensional space–time S33R. The construction is based on an ansatz
built out of special coordinates on S3. The requirement for finite energy introduce
boundary conditions that determine an infinite discrete spectrum of frequencies for
the oscillating solutions. For the case where the target space is the sphere S2, we
obtain static soliton solutions with nontrivial Hopf topological charges. In addition,
such Hopfions can oscillate in time, preserving their topological Hopf charge, with
any of the frequencies belonging to that infinite discrete spectrum