穿越弦沼泽：沼泽地中的CMB双折射
Wading the String Bog: CMB Birefringence in the Swampland
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中文总结 AI 辅助
该研究提出宇宙双折射观测可检验沼泽地猜想，指出超轻标量双折射受弱引力猜想约束，薄轴子畴壁或能解释双折射，相关场景可通过POLARBEAR等实验区分。
中文摘要 AI 辅助
我们指出，宇宙双折射的观测或许能为沼泽地（Swampland）猜想提供直接的实验检验。超轻标量场双折射机制受弱引力猜想（Weak Gravity Conjecture）约束，限制了其参数空间。反之，若确认CMB双折射由超轻标量导致，可能会给沼泽地框架带来问题。在不修正沼泽地理念的前提下解决这些困难，指向了薄轴子畴壁，其无需传播超轻自由度即可解释双折射。重要的是，这些关于宇宙双折射的冲突场景可通过搜寻或排除双折射各向异性来实验区分，POLARBEAR、Simons Observatory和LiteBIRD可对其进行测量。我们还注意到，宇宙双折射可观测量通过类萨哈罗夫（Sakharov）不对称性产生：线性极化首先在宇宙学中生成，随后在最后散射后被宇称破缺动力学扭转。
英文摘要
We point out that observations of cosmic birefringence may provide direct experimental tests of Swampland conjectures. Ultralight scalar field birefringence mechanisms are constrained by Weak Gravity Conjecture, limiting their parameter space. Conversely, confirming that CMB birefringence is caused by ultralight scalars could spell problems for the Swampland framework. Resolving these difficulties without a revision of Swampland ideology points toward thin axionic domain walls, which can explain birefringence without propagating ultralight degrees of freedom. Importantly these conflicting scenarios for cosmic birefringence could be experimentally distinguished by a search for, or exclusion of, birefringence anisotropies, that could be measured by POLARBEAR, Simons Observatory and LiteBIRD. We also note that cosmic birefringence observables emerge via a Sakharov-like asymmetry, where linear polarization is first generated cosmologically and subsequently twisted by a parity-violating dynamics after last scattering.
