Multivalued fields for defects in spacetime and gravity

Session will be devoted to multivalued field theories and the geometric theory of defects. Defects in elastic media specity the plastic properties of solids, and their theoretical description is of great importance for material science. If defects are present, the basic variables of elasticity theory (the displacement vector field and the rotational angle field) become multivalued. Certain higher derivatives of these fields, however, remain single-valued and define a Riemann–Cartan geometry that accommodates natrually a theory of gravity with torsion, in which curvature and torsion are built from rotational and translational defects. Since these two defects are dependent of each other, physical phenomena possess equivalent descriptions, the most famous example being Einstein's teleparallel theory of gravity.