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SUMMARY:Particle creation in the Early Universe: comparing canonical and p
 ath integral approaches
DTSTART;VALUE=DATE-TIME:20261030T061500Z
DTEND;VALUE=DATE-TIME:20261030T063000Z
DTSTAMP;VALUE=DATE-TIME:20261030T193915Z
UID:indico-contribution-6275@cern.ch
DESCRIPTION:Speakers: Tatyana Shestakova (Department of Theoretical and Co
 mputational Physics\, Southern Federal University)\nWe consider particle c
 reation of a non‑conformal scalar field in the Early Universe. The devia
 tion from conformality is assumed to be small\, which allows us to treat t
 he terms describing the non-conformal scalar field as a perturbation. We d
 erive the Schrödinger equation for the system of gravitational and scalar
  fields from the path integral making use of a holomorphic representation 
 for the scalar field. In the conformal case\, the equation is solved exact
 ly. In the case of a non-conformal field\, we use the perturbation theory\
 , and some new features are revealed. When deriving the Schrödinger equat
 ion\, we obtain an operator that maps the states of the Fock space with a 
 certain number of particles and antiparticles at time *t* to states corres
 ponding to a subsequent moment of time. The operator appears entirely due 
 to changing of a basis in the Fock space with time. We compare our results
  with those obtained using the method of diagonalizing the Hamiltonian in 
 the canonical formalism and find that the results are fully consistent. In
  perspective\, we consider the path integral approach as an additional too
 l for studying particle creation in a gravitational field and cosmological
  perturbations.\n\nhttps://indico.particle.mephi.ru/event/626/contribution
 s/6275/
LOCATION: Conference Hall 4
URL:https://indico.particle.mephi.ru/event/626/contributions/6275/
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