https://doi.org/10.1140/epjc/s10052-024-13108-7
Regular Article - Theoretical Physics
Revisiting the averaged annihilation rate of thermal relics at low temperature
1
Université Claude Bernard Lyon 1, CNRS/IN2P3, Institut de Physique des 2 Infinis de Lyon, UMR 5822, 69622, Villeurbanne, France
2
Theoretical Physics Department, CERN, 1211, Geneva 23, Switzerland
3
Institut Universitaire de France (IUF), 75005, Paris, France
c
marco.palmiotto@univ-lyon1.fr
Received:
24
April
2024
Accepted:
7
July
2024
Published online:
27
July
2024
We derive a low-temperature expansion of the formula to compute the average annihilation rate 
for dark matter in 
-symmetric models, both in the absence and the presence of mass degeneracy in the spectrum near the dark matter candidate. We show that the result obtained in the absence of mass degeneracy is compatible with the analytic formulae in the literature, and that it has a better numerical behaviour for low temperatures. We also provide as ancillary files two Wolfram Mathematica notebooks, which perform the two expansions at any order.
© The Author(s) 2024
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