暗磁单极子、隐藏扇区的界限及宇宙学意义
Dark Monopoles, Bounds on Hidden Sectors, and Cosmological Implications
AI总结：
研究早期宇宙热相变产生的隐藏扇区磁单极子，通过分析其丰度，给出对称破缺尺度等条件限制，指出只有满足特定条件才能恢复标准宇宙学，为暗物质模型构建及宇宙学研究提供了相关界限。
AI中文摘要：
隐藏扇区是弦理论紧致化的一个普遍预测，为暗物质模型构建提供了广阔前景。我们考虑早期宇宙热相变产生并随后通过对湮灭稀释的隐藏扇区磁单极子情况。我们表明，对于对称破缺尺度$\gtrsim 100\, \text{PeV}$，磁单极子丰度高得不可接受，会使宇宙闭合。我们的界限对隐藏扇区初始能量密度分数的变化具有鲁棒性，仅对该量呈现弱幂律依赖。在多个隐藏扇区的情况下界限显著收紧。只有在以下情况之一成立时才能恢复标准宇宙学：不存在隐藏扇区；隐藏扇区不存在对称破缺尺度高于100 PeV的磁单极子；每个产生磁单极子的隐藏扇区在再加热后的最高温度低于其对称破缺尺度；或者磁单极子丰度在早期物质主导时期被稀释。
英文摘要：
Hidden sectors are a generic prediction of string theory compactifications and result in a promising landscape for dark matter model building. We consider the case of hidden sector magnetic monopoles produced via a thermal phase transition in the early Universe and subsequently diluted by pair annihilation. We show that for symmetry-breaking scales $\gtrsim 100\, \text{PeV}$, the monopole abundance is unacceptably high, overclosing the Universe. Our bounds are robust against variations in the initial fraction of energy density deposited in the hidden sector, exhibiting only a weak power-law dependence on this quantity. The bound is substantially tightened in the case of multiple hidden sectors. The standard cosmology may only be recovered if one of the following is true: the hidden sector(s) are non-existent, the hidden sectors have no monopoles with symmetry-breaking scale above 100 PeV, the maximum temperature of each monopole-producing hidden sector after reheating is below its symmetry-breaking scale, or the monopole abundance is diluted during a period of early matter domination.
