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SUMMARY:Kévin Nguyen (King's College)
DTSTART:20201008T140000Z
DTEND:20201008T150000Z
DTSTAMP:20260423T024802Z
UID:HEPTUW/7
DESCRIPTION:Title: <a href="https://researchseminars.org/talk/HEPTUW/7/">T
 he effective action of superrotation modes</a>\nby Kévin Nguyen (King's C
 ollege) as part of HEP seminars TU Wien (Vienna)\n\n\nAbstract\nStarting f
 rom an analysis of four-dimensional asymptotically flat gravity in first o
 rder formulation\, we show that superrotation reparametrization modes are 
 governed by an Alekseev--Shatashvili action on the celestial sphere. This 
 two-dimensional conformal theory describes spontaneous symmetry breaking o
 f Virasoro superrotations together with the explicit symmetry breaking of 
 more general Diff(S2) superrotations. We arrive at this result by first re
 formulating the asymptotic field equations and symmetries of the radiative
  vacuum sector in terms of a Chern--Simons theory at null infinity\, and s
 ubsequently performing a Hamiltonian reduction of this theory onto the cel
 estial sphere.\n
LOCATION:https://researchseminars.org/talk/HEPTUW/7/
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