August 21 at 13:00 - 14:30, 2020
Dr. Takuya Shimazaki (Researcher, Hadron Theory Group, The University of Tokyo)
via Zoom

Dykhne–Davis–Pechukas (DDP) method is a common approximation scheme for the transition probability in two-level quantum systems, as realized in the Landau–Zener effect, leading to an exponentially damping form comparable to the Schwinger pair production rate. We analyze the foundation of the DDP method using a modern complex technique inspired by the Lefschetz-thimble method. We derive an alternative and more adaptive formula that is useful even when the DDP method is inapplicable. As a benchmark, we study the modified Landau–Zener model and compare results from the DDP and our methods. We then revisit a derivation of the Schwinger Mechanism of particle production under electric fields using the DDP and our methods. We find that the DDP method gets worse for the Sauter type of short-lived electric pulse, while our method is still a reasonable approximation. We also study the Dynamically Assisted Schwinger Mechanism in two methods.

*Detailed information about the seminar refer to the email.


  1. K. Fukushima, T. Shimazaki, Annals Phys. 415 (2020) 168111 DOI: 10.1016/j.aop.2020.168111

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