Thermal regularization of t-channel singularities in cosmology and particle physics: the general case
arXiv:2212.00561 · doi:10.1007/JHEP06(2023)006
Abstract
This paper presents a~way to regularize the -channel singularity (which appears when a~massive, stable -channel mediator of a~given process is allowed to be on-shell, making the cross section infinite) in a~general case of particles of any spin (0,~\nicefrac12,~1) interacting within a~thermal medium. Those interactions result in a~finite lifetime of the mediator and allow to introduce an~effective momentum- and temperature-dependent width. As a result, the would-be-singular cross section becomes finite. A~complete derivation and an analytical result for the width are provided. For an illustration, the method is used to calculate the thermal widths and cross sections within the~Vector-Fermion Dark Matter model.
arXiv commentv3: 31 pages, 10 figures, 9 tables; matches the revised version to appear in JHEP
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