Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: New effect in wave-packet scatterings of quantum fields: Saddle points,
  Lefschetz thimbles, and Stokes phenomenon   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 $\phi$ by another
intermediate heavy scalar $\Phi$, in the Gaussian wave-packet formalism:
$\phi\phi\to\Phi\to\phi\phi$. This contribution can be interpreted as an
"in-time-boundary effect" of $\Phi$ for the corresponding $\Phi\to\phi\phi$
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.

23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
30
The categories of this paper are: q-alg
25
The categories of this paper are: patt-sol
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
2
The categories of this paper are: math
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph