BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:The topology of smectics - Prof. Randy Kamien\, Physics Department
 \, University of Pennsylvania
DTSTART:20110614T131500Z
DTEND:20110614T141500Z
UID:TALK31453@talks.cam.ac.uk
CONTACT:Dr G Moller
DESCRIPTION:The homotopy theory of topological defects in ordered media fa
 ils to completely characterize systems with broken translational symmetry.
  We argue that the problem can be understood in terms of the lack of rotat
 ional Goldstone modes in such systems and provide an alternate approach th
 at correctly accounts for the interaction between translations and rotatio
 ns. Dislocations are associated\, as usual\, with branch points in a phase
  field\, whereas disclinations arise as critical points and singularities 
 in the phase field. We introduce a three-dimensional model for two-dimensi
 onal smectics that clarifies the topology of disclinations and geometrical
 ly captures known results without the need to add compatibility conditions
 . Our work suggests natural generalizations of the two-dimensional smectic
  theory to higher dimensions and to crystals.
LOCATION:TCM Seminar Room\, Cavendish Laboratory
END:VEVENT
END:VCALENDAR