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arXiv · 1405.6921

Bremsstrahlung and Gamma Ray Lines in 3 Scenarios of Dark Matter Annihilation

Federica Giacchino·Laura Lopez-Honorez·Michel H. G. Tytgat
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Abstract

Gamma ray spectral features are of interest for indirect searches of dark matter (DM). Following Barger et al, we consider 3 simple scenarios of DM that annihilates into Standard Model (SM) fermion pairs. Scenario 1 is a Majorana DM candidate coupled to a charged scalar, scenario 2 is a Majorana DM coupled to a charged gauge boson and scenario 3 is a real scalar DM coupled a charged vector-like fermion. As shown by Barger et al, these 3 scenarios share precisely the same internal Bremsstrahlung spectral signature into gamma rays. Their phenomenology is however distinct. In particular for annihilation into light SM fermions, in the chiral limit, the 2-body annihilation cross section is p-wave suppressed for the Majorana candidates while it is d-wave suppressed for the real scalar. In the present work we study the annihilation into 2 gammas, showing that these three scenarios have distinct, and so potentially distinguishable, spectral signatures into gamma rays. In the case of the real scalar candidate we provide a new calculation of the amplitude for annihilation into 2 gammas.

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Federica Giacchino, Laura Lopez-Honorez, Michel H. G. Tytgat. 2014-05-27. Bremsstrahlung and Gamma Ray Lines in 3 Scenarios of Dark Matter Annihilation. https://doi.org/10.1088/1475-7516%2F2014%2F08%2F046

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