Speaker
Description
Topological defects play a central role in shaping the structure, dynamics, and emergent behaviour of active matter systems. In soft matter physics, the nature of these defects is dictated by the symmetry of the underlying field description: polar systems support integer-charged defects (±1), while nematic systems—with head-tail symmetry—admit half-integer charges (±½). Active matter, particularly in biological and synthetic active nematics, has traditionally been modelled using purely nematic symmetry, where ±½ defects, their creation, annihilation, and dynamics governs the large-scale flows and macroscopic behaviour of the system. However in the physical world, active materials a vast variety of systems — such as epithelial tissues, bacterial colonies — often exhibit mixed symmetries, where polar and nematic components coexist and interact. This mixed structure enriches the defect landscape: polar distortions can bias the orientation or motility of ±½ nematic defects, alter defect unbinding dynamics, and affect defect shape and motion as a result of the underlying coupled fields. Understanding how these different symmetries interplay is essential for detailed hydrodynamic description of active matter.
