Dark matter in axion landscape

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• 作者：Ryuji Daido^a ; ^{daido@tuhep.phys.tohoku.ac.jp} ; Takeshi Kobayashi^b ; ^c ; ^{takeshi.kobayashi@sissa.it} ; Fuminobu Takahashi^a ; ^d ; ^{fumi@tuhep.phys.tohoku.ac.jp}
• 刊名：Physics Letters B
• 出版年：2017
• 出版时间：10 February 2017
• 年：2017
• 卷：765
• 期：Complete
• 页码：293-299
• 全文大小：410 K
• 卷排序：765

文摘

If there are a plethora of axions in nature, they may have a complicated potential and create an axion landscape. We study a possibility that one of the axions is so light that it is cosmologically stable, explaining the observed dark matter density. In particular we focus on a case in which two (or more) shift-symmetry breaking terms conspire to make the axion sufficiently light at the potential minimum. In this case the axion has a flat-bottomed potential. In contrast to the case in which a single cosine term dominates the potential, the axion abundance as well as its isocurvature perturbations are significantly suppressed. This allows an axion with a rather large mass to serve as dark matter without fine-tuning of the initial misalignment, and further makes higher-scale inflation to be consistent with the scenario.