标题： 极化约束上的各向异性宇宙双折射从CMB B模式 显示英文标题

标题： Constraints on Anisotropic Cosmic Birefringence from CMB B-mode Polarization

摘要： 宇宙双折射$-$光线穿越宇宙时偏振面的旋转$-$提供了直接观测标准模型之外宇称破坏物理的一个窗口。 在这项工作中，我们重新审视了宇宙双折射的各向异性成分，这会导致宇宙微波背景（CMB）中$B$模式偏振的产生。 使用超越薄最后散射面近似的精确理论处理，我们利用来自 SPTpol、ACT、POLARBEAR 和 BICEP 的联合偏振数据约束了各向异性双折射的幅度。 联合分析得出的最佳拟合幅度为$A_{\rm CB} = 0.42^{+0.40}_{-0.34} \times 10^{-4}$，在$2\sigma$范围内与零一致，并且我们给出了 95\% 置信水平上限$A_{\rm CB} < 1 \times 10^{-4}$。 该限制不是由单一实验主导的，并且在可能存在的各向同性旋转角度下仍然是稳健的。 这些结果为来自 CMB$B$模式偏振的各向异性宇宙双折射提供了主要限制，并展示了即将进行的实验提高早期宇宙宇称破坏效应敏感性的潜力。 显示英文摘要

摘要： Cosmic birefringence$-$the rotation of the polarization plane of light as it traverses the universe$-$offers a direct observational window into parity-violating physics beyond the Standard Model. In this work, we revisit the anisotropic component of cosmic birefringence, which leads to the generation of $B$-mode polarization in the cosmic microwave background (CMB). Using an exact theoretical treatment beyond the thin last-scattering surface approximation, we constrain the amplitude of anisotropic birefringence with combined polarization data from SPTpol, ACT, POLARBEAR, and BICEP. The joint analysis yields a best-fit amplitude of $A_{\rm CB} = 0.42^{+0.40}_{-0.34} \times 10^{-4}$, consistent with zero within $2\sigma$, and we place a 95\% confidence-level upper bound of $A_{\rm CB} < 1 \times 10^{-4}$. The constraint is not dominated by any single experiment and remains robust under the inclusion of a possible isotropic rotation angle. These results provide leading constraints on anisotropic cosmic birefringence from CMB $B$-mode polarization and illustrate the potential of upcoming experiments to improve sensitivity to parity-violating effects in the early universe.