We perform calculations of dark photon production and decay in the early universe for ranges of dark photon masses and vacuum coupling with standard model photons. Simultaneously and self-consistently with dark photon production and decay, our calculations include a complete treatment of weak decoupling and big bang nucleosynthesis (BBN) physics. These calculations incorporate all relevant weak, electromagnetic, and strong nuclear reactions, including charge-changing (isospin-changing) lepton capture and decay processes. They reveal a rich interplay of dark photon production, decay, and associated out-of-equilibrium transport of entropy into the decoupling neutrino seas. Most importantly, the self-consistent nature of our simulations allows us to capture the magnitude and phasing of entropy injection and dilution. Entropy injection-induced alteration of the time-temperature-scale factor relation during weak decoupling and BBN leads to changes in the light element abundance yields and the total radiation content (as parametrized by $N_{\rm eff}$). These changes suggest ways to extend previous dark photon BBN constraints. However, our calculations also identify ranges of dark photon mass and couplings not yet constrained, but perhaps accessible and probable, in future Stage-4 cosmic microwave background experiments and future high precision primordial deuterium abundance measurements.

中文翻译：

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用大爆炸核合成探测早期宇宙中的暗光子

我们对早期宇宙中暗光子的产生和衰变进行计算，以计算暗光子质量范围以及与标准模型光子的真空耦合。与暗光子的产生和衰变同时且自洽，我们的计算包括对弱解耦和大爆炸核合成 (BBN) 物理学的完整处理。这些计算结合了所有相关的弱核反应、电磁反应和强核反应，包括电荷变化（同位旋变化）轻子俘获和衰变过程。它们揭示了暗光子的产生、衰变和相关的熵向解耦中微子海的非平衡传输之间的丰富相互作用。最重要的是，我们模拟的自洽性质使我们能够捕捉熵注入和稀释的幅度和相位。在弱解耦和 BBN 期间，熵注入引起的时间-温度-尺度因子关系的改变导致轻元素丰度产率和总辐射含量的变化（由 $N_{\rm eff}$ 参数化）。这些变化提出了扩展先前暗光子 BBN 约束的方法。然而，我们的计算还确定了暗光子质量和耦合的范围，但在未来的第 4 阶段宇宙微波背景实验和未来的高精度原始氘丰度测量中，暗光子的质量和耦合范围可能尚未受到限制，但可能是可访问和可能的。