Session CB - Field Theory; Astronomy and Astrophysics; Life on Mars.
MIXED session, Friday morning, November 15
Henry Oliver F, Holiday Inn
Phase transitions in the early universe may have resulted in the formation of topological defects such as cosmic strings. Such phase transitions are usually viewed as being caused by the breaking of the symmetry of a Higgs field occurring in a space-time whose geometry is Riemannian. While Riemannian geometries accurately describe the structure of space-time on the large scale, gauge theories of gravitation suggest that on the small scale space-time may be Riemann-Cartan. In a Rieman-Cartan geometry a torsion field exists in addition to the usual metric tensor. It is plausible that early in its history the universe was Riemann-Cartan and that a phase transition to Riemannian geometry has occurred. In this scenario one might expect string defects due to the torsion field to have formed. We have shown that torsion fields can form cosmic strings. Several examples of these torsion strings are considered. We also examine particle motion in and around the strings. We find that when torsion fields are present particles sense the string even when the space -time is flat.