New effect in wave-packet scatterings of quantum fields: Saddle points, Lefschetz thimbles, and Stokes phenomenon

Date

2021/05/11(Tue)11:00〜12:00

Venue

Online (Zoom)

Speaker

Prof. Kin-ya Oda ( Tokyo Woman’s Christian University )

Language

English

URL

Contact

khat-AT-post.kek.jp


Overview

We find a new contribution in wave-packet scatterings, which has been overlooked in the standard formulation of S-matrix. As a concrete example, we consider a two-to-two scattering of light scalars ϕ by another intermediate heavy scalar Φ, in the Gaussian wave-packet formalism: ϕϕ→Φ→ϕϕ. This contribution can be interpreted as an “in-time-boundary effect” of Φ for the corresponding Φ→ϕϕ decay, proposed by Ishikawa et al., with a newly found modification that would cure the previously observed ultraviolet divergence. We show that such an effect can be understood as a Stokes phenomenon in an integral over complex energy plane: The number of relevant saddle points and Lefschetz thimbles (steepest descent paths) discretely changes depending on the configurations of initial and final states in the scattering.

Release date 2021/04/21 Updated 2024/08/07