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SUMMARY:Anne Moreau (U. Paris Saclay)
DTSTART:20210107T100000Z
DTEND:20210107T113000Z
DTSTAMP:20260422T225723Z
UID:Darboux/1
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/Darboux/1/">
 Nilpotent Slodowy slices and W-algebras</a>\nby Anne Moreau (U. Paris Sacl
 ay) as part of Darboux Seminar\n\nLecture held in Amphi Charpak\, Campus P
 ierre et Marie Curie\, Tour 22 RdJ.\n\nAbstract\nTo any vertex algebra one
  can attach in a canonical way a certain Poisson variety\, called the asso
 ciated variety. Nilpotent Slodowy slices appear as associated varieties of
  admissible (simple) W-algebras. They also appear as Higgs branches of the
  Argyres-Douglas theories in 4d N=2 SCFT’s. These two facts are linked b
 y the so-called Higgs branch conjecture. In this talk I will explain how t
 o exploit the geometry of nilpotent Slodowy slices to study some propertie
 s of W-algebras whose motivation stems from physics. This is a joint work 
 with Tomoyuki Arakawa and Jethro van Ekeren (still in preparation).\n
LOCATION:https://researchseminars.org/talk/Darboux/1/
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SUMMARY:Johannes Kellendonk (Institut Camille Jordan\, Lyon)
DTSTART:20210204T100000Z
DTEND:20210204T113000Z
DTSTAMP:20260422T225723Z
UID:Darboux/2
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/Darboux/2/">
 The non-commutative topological approach to topological phases with protec
 ting symmetry</a>\nby Johannes Kellendonk (Institut Camille Jordan\, Lyon)
  as part of Darboux Seminar\n\nLecture held in Zoom.\n\nAbstract\nIn this 
 talk we review the K-theoretic description of topological phases of insula
 tors and superconductors in the effective one particle approximation. In t
 hat approximation\, an insulator (or superconductor) is described by a Ham
 iltonian whose spectrum has a gap at the Fermi energy. Two Hamiltonians be
 long to the same topological phase if they can be deformed into each other
  without closing the gap. For this to be well-defined\, it is important to
  specify the space of possible Hamiltonians with its topology. When this s
 pace is taken to be a C*-algebra equipped with a real structure and a grad
 ing\, one can use real graded K-theory and its dual (K-homology or cyclic 
 cohomology) to describe the topological phases and their numerical topolog
 ical invariants.\n
LOCATION:https://researchseminars.org/talk/Darboux/2/
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