Weekly Seminars for September 2018
Monday September 24th, 2018 - TBD
  ICRANet Pescara (Meeting room, 1st Floor)
ICRANet Seminar
Speaker: Prof. Sang Pyo Kim

Institution: Dept. of Physics, Kunsan National University, Kunsan 54150 , Korea

Title: QEDPhenomena in de Sitter Space‚Äč
The QED action for uniform electric and parallel magnetic fields in dS space consists of two parts: the vacuum polarization and the vacuum persistence, twice of the imaginary part. The vacuum persistence is related to the Schwinger effect of spontaneous pair production in dS space. We obtain a pair production rate in the electromagnetic field which agrees with the known Schwinger result in the limit of Minkowski spacetime and with Hawking radiation in dS space in the zero electromagnetic field limit. Using the zeta function regularization scheme, we calculate the induced current and examine the effect of a magnetic field on the vacuum expectation value of the current operator. We discuss Schwinger effect as a possible scenario for magnetogenesis. We employ the in-out formalism introduced by Schwinger and DeWitt and apply the gamma-function regularization to find the one-loop QED action in the proper-time integral representation in dS space. The one-loop effective action becomesthe famous Heisenberg-Euler-Schwinger action in the limit of Minkowski spacetime and yieldsthe one-loop gravity action in the zero electromagnetic field limit, which is a nonperturbative analog of Heisenberg-Euler-Schwinger QED action.Finally we discuss the physical implications of QED vacuum polarization in cosmology as well as astrophysics.
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