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Effects of Bound States on Dark Matter Annihilation

An, Haipeng and Wise, Mark B. and Zhang, Yue (2016) Effects of Bound States on Dark Matter Annihilation. Physical Review D, 93 (11). Art. No. 115020. ISSN 2470-0010. doi:10.1103/PhysRevD.93.115020.

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We study the impact of bound state formation on dark matter annihilation rates in models where dark matter interacts via a light mediator, the dark photon. We derive the general cross section for radiative capture into all possible bound states, and point out its nontrivial dependence on the dark matter velocity and the dark photon mass. For indirect detection, our result shows that dark matter annihilation inside bound states can play an important role in enhancing signal rates over the rate for direct dark matter annihilation with Sommerfeld enhancement. The effects are strongest for large dark gauge coupling and when the dark photon mass is smaller than the typical momentum of dark matter in the Galaxy. As an example, we show that for thermal dark matter the Fermi gamma ray constraint is substantially increased once bound state effects are taken into account. We also find that bound state effects are not important for dark matter annihilation during the freeze-out and recombination epochs.

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Additional Information:© 2016 American Physical Society. Received 14 April 2016; published 15 June 2016. We thank Clifford Cheung, Walter D. Goldberger and Maxim Pospelov for the useful discussions. This work is supported by U.S. DOE Grants No. DE-SC0011632, and No. DE-SC0010255, and by the Gordon and Betty Moore Foundation through Grant No. 776 to the Caltech Moore Center for Theoretical Cosmology and Physics. We are also grateful for the support provided by the Walter Burke Institute for Theoretical Physics. H. A. acknowledges the hospitality from the Perimeter Institute for Theoretical Physics.
Group:Walter Burke Institute for Theoretical Physics, Moore Center for Theoretical Cosmology and Physics
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Department of Energy (DOE)DE-SC0011632
Department of Energy (DOE)DE-SC0010255
Gordon and Betty Moore Foundation776
Walter Burke Institute for Theoretical Physics, CaltechUNSPECIFIED
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Issue or Number:11
Record Number:CaltechAUTHORS:20160411-175600335
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Official Citation:Effects of bound states on dark matter annihilation Haipeng An, Mark B. Wise, and Yue Zhang Phys. Rev. D 93, 115020
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:66065
Deposited By: Joy Painter
Deposited On:12 Apr 2016 17:35
Last Modified:10 Nov 2021 23:52

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