http://arxiv.org/abs/2101.07634
We revisit gravitational particle production from the Stokes phenomenon viewpoint, which is crucial to understand asymptotic behavior of mode functions with a time dependent frequency. One of our purposes of this work is to show how the analysis focusing on the Stokes phenomenon can be used to analytically estimate non-perturbative particle production rate. In particular, with several examples of time-dependent background, we examine some methods that make the analysis more practical. Specifically, we consider the particle production in simple expanding backgrounds, $R^2$ inflation, and a model with smoothly changing mass. Since some of our models show difficulties in analyzing Stokes phenomenon, we discuss simplification of the problem and the accuracy of analytic estimation within our approximations. We also propose an approximation to take into account the most important contribution among infinite number of turning points and poles, which greatly simplifies the problem, but still gives a good analytic estimation.
S. Hashiba and Y. Yamada
Wed, 20 Jan 21
2/61
Comments: 23 + 17 pages, 13 + 7 figures
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