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SUMMARY:Masazumi Honda (RIKEN)\, "Picard-Lefschetz theory and Gravitationa
 l path integral"
DTSTART:20260528T060000Z
DTEND:20260528T070000Z
DTSTAMP:20260527T152300Z
UID:indico-event-1288@indico.ibs.re.kr
DESCRIPTION:We revisit the path-integral approach to the wave function of 
 the Universe by utilizing Lefschetz thimble analyses and resurgence theory
 . The traditional Euclidean path-integral of gravity has the notorious amb
 iguity of the direction of Wick rotation. In contrast\, the Lorentzian met
 hod can be formulated concretely with the Picard-Lefschetz theory. Yet\, a
  challenge remains: the physical parameter space lies on a Stokes line\, m
 eaning that the Lefschetz-thimble structure is still unclear. Through comp
 lex deformations\, we resolve this issue by uniquely identifying the thimb
 le structure. This leads to the tunneling wave function\, as opposed to th
 e no-boundary wave function\, offering a more rigorous proof of the previo
 us results. Further exploring the parameter space\, we discover rich struc
 tures: the ambiguity of the Borel resummation of perturbative series aroun
 d the tunneling saddle points is exactly canceled by the ambiguity of the 
 contributions from no-boundary saddle points. This indicates that resurgen
 ce also works in quantum cosmology\, particularly in the minisuperspace mo
 del.\n\nhttps://indico.ibs.re.kr/event/1288/
LOCATION:CTPU Seminar room (Theory Bldg\, 4F)
URL:https://indico.ibs.re.kr/event/1288/
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