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arXiv 0905.1312hep-phastro-ph.COastro-ph.HE
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Cosmic Ray反常和暗物质湮灭到μ子

Cosmic Ray Anomalies and Dark Matter Annihilation to Muons via a Higgs Portal Hidden Sector

Kazunori Kohri, John McDonald, Narendra Sahu

备注：
24 pages, 4 figures. Expanded discussion, conclusions unchanged. Version to be published in Physical Review D
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摘要：

湮灭暗物质（DM）模型的基础上，一个标量隐藏的部门与希格斯门耦合的标准模型被认为是一个可能的解释最近观察到的宇宙射线过剩。两个版本的模型进行了研究，一个与非热DM的起源的助推因子和索末菲增强。在非热DM的情况下，增加了四个在U（1）_{X}对称下变换的隐扇区标量。最重的标量解耦并随后衰变为DM标量，因此提供了解释当前DM湮灭率所必需的增强因子。湮灭标量的质量被限制在< 600 GeV，以使模型保持微扰。U（1）_{X}在电弱跃迁处破缺到Z_2，使O（100）MeV的暗扇形标量与Higgs粒子混合。DM标量湮灭为这些光标量，这些光标量随后通过希格斯混合衰变为两个μ ^{+} μ ^{-}对，因此产生了没有反质子的正电子过剩。衰变到μ^{+}μ^{-}而不是e^{+}e^{-}是必要的，以确保足够快的光标量衰变速率，从而避免核合成中的光标量支配。在索末菲增强的版本中，只有三个新的标量是必要的。TeV尺度的DM质量可以容纳，允许更高能量的电子加上正电子过剩和更低能量的PAMELA正电子过剩被解释。DM湮灭为两个μ^{+}μ^{-}对，如在非热模型中。这种湮没模式可能是赞成最近的观测电子加正电子过剩费米和HESS。

英文摘要：

Annihilating dark matter (DM) models based on a scalar hidden sector with Higgs portal-like couplings to the Standard Model are considered as a possible explanation for recently observed cosmic ray excesses. Two versions of the model are studied, one with non-thermal DM as the origin of the boost factor and one with Sommerfeld enhancement. In the case of non-thermal DM, four hidden sector scalars which transform under a U(1)_{X} symmetry are added. The heaviest scalars decouple and later decay to DM scalars, so providing the boost factor necessary to explain the present DM annihilation rate. The mass of the annihilating scalars is limited to < 600 GeV for the model to remain perturbative. U(1)_{X} breaking to Z_2 at the electroweak transition mixes light O(100) MeV hidden sector scalars with the Higgs. The DM scalars annihilate to these light scalars, which subsequently decay to two mu^{+} mu^{-} pairs via Higgs mixing, so generating a positron excess without antiprotons. Decay to μ^{+}μ^{-} rather than e^{+}e^{-} is necessary to ensure a fast enough light scalar decay rate to evade light scalar domination at nucleosynthesis. In the version with Sommerfeld enhancement only three new scalars are necessary. TeV scale DM masses can be accomodated, allowing both the higher energy electron plus positron excess and the lower energy PAMELA positron excess to be explained. DM annihilates to two μ^{+}μ^{-} pairs as in the non-thermal model. This annihilation mode may be favoured by recent observations of the electron plus positron excess by FERMI and HESS.

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