postscript
3 Vortices with Non-symmetric ...
Abstract...
Acknowledgements...
We have studied the existence and stability properties of defects (domain walls
and vortices) with non-symmetric core and non-trivial winding at infinity.
These defects arise in scalar field theories that exhibit an explicit breaking
of a global symmetry, 
for domain wall and 
for vortices. In their
spectrum and for a particular range of parameters topologically stable and
unstable defects appear with either symmetric or non-symmetric cores. Possible
implications for the cosmology of the early universe are the following: With
regard to the case of domain walls with a symmetric core (saddle and high
Napoleon hat potentials) a possible embedding of such configurations in a
realistic 
Higgs electroweak model may realize a new mechanism for
baryogenesis at the electroweak phase transition. Defect mediated baryogenesis
has been so far only successfully implemented at scales introduced near or above
the electroweak one (Brandenberger et al. (1996)). These mechanisms are based on unsuppressed
B+L violating sphaleron transitions taking place in the symmetric core of the
defects during scattering processes (Cohen et al. (1993)). As a result of our work the
question of existence of electroweak domain walls with a symmetric core now
translates to whether in the most general electroweak Lagrangian with two Higgs
doublets potential energies of the ``saddle hat'' or ``high Napoleon hat'' type
exist for an appropriate range of parameters. As the parity symmetry in these
models is broken both spontaneously an explicitly the expected domain walls in
their spectrum are certainly of the non-topological type. Moreover it would be
of interest to see if such defects arise at a second order electroweak phase
transition. Our observation of non-spherical collapse of wall bubbles with
non-symmetric core may imply that the domain wall network simulations need to
be re-examined for parameter ranges where a non-symmetric core in energetically
favoured.
With regard to our demonstration of existence of vortices with non-symmetric
core it becomes immediately suggestive the existence of a new kind of a bosonic
superconducting string, possessing massive charge carriers (Witten (1985)). This
would be the case if our model is properly coupled to a 
gauge field.The
physics of fermions introduced to such a system is also open for investigation.
The astrophysical and cosmological role of superconducting strings has been
extensively investigated in the literature (Ostriker et al. (1986), Davis & Shellard (1988), Davis & Shellard (1988)).