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SUMMARY:Yichul Choi (Stony Brook)
DTSTART:20220531T150000Z
DTEND:20220531T160000Z
DTSTAMP:20260423T052447Z
UID:SymSem/13
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/SymSem/13/">
 Higher Berry Phase of Free Dirac Fermions</a>\nby Yichul Choi (Stony Brook
 ) as part of Symmetry Seminar\n\n\nAbstract\nThe infrared fixed point of a
  trivially gapped quantum field theory is described by an invertible field
  theory\, which captures its response to various external background field
 s. The set of background fields can include spacetime-dependent coupling c
 onstants\, in which case we call the corresponding invertible theory a par
 ameterized invertible field theory. The partition function of a parameteri
 zed invertible field theory is called a higher Berry phase\, as it capture
 s the response of the theory to the adiabatic variation of the coupling co
 nstants across spacetime. I'll discuss a class of such parameterized inver
 tible field theories arising from free Dirac fermions with spacetime-depen
 dent mass parameters. The universal form of the higher Berry curvature wil
 l be derived using the APS index theorem\, and an example of a nontrivial 
 parameterized invertible theory with a vanishing Berry curvature will be e
 xplained.\n
LOCATION:https://researchseminars.org/talk/SymSem/13/
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