Low-temperature enhancement of semi-annihilation and the AMS-02 positron anomaly

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Title
Low-temperature enhancement of semi-annihilation and the AMS-02 positron anomaly
Author(s)
Yi Cai; Andrew Spray
Publication Date
2018-10
Journal
JOURNAL OF HIGH ENERGY PHYSICS, v.2018, no.10, pp.075 -
Publisher
SPRINGER
Abstract
Semi-annihilation is a generic feature of particle dark matter that is most easily probed by cosmic ray experiments. We explore models where the semi-annihilation cross section is enhanced at late times and low temperatures by the presence of an s-channel resonance near threshold. The relic density is then sensitive to the evolution of the dark matter temperature, and we compute expressions for the associated Boltzmann equation valid in general semi-annihilating models. At late times, a self-heating effect warms the dark matter, allowing number-changing processes to remain effective long after kinetic decoupling of the dark and visible sectors. This allows the semi-annihilation signal today to be enhanced by up to five orders of magnitude over the thermal relic cross section. As a case study, we apply this to a dark matter explanation of the positron excess seen by AMS-02. We see that unlike annihilating dark matter, our model has no difficulty fitting the data while also giving the correct relic density. However, constraints from the CMB and ��-rays from the galactic centre do restrict the preferred regions of parameter space. (c) 2018, The Author(s)
URI
https://pr.ibs.re.kr/handle/8788114/5128
ISSN
1029-8479
Appears in Collections:
Center for Fundamental Theory(순수물리이론 연구단) > Journal Papers (저널논문)
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