论文标题
气泡墙上的思考
Reflections on Bubble Walls
论文作者
论文摘要
我们讨论了在存在巨大的深色光子存在下扩展气泡壁的动力学，其质量在越过墙壁时会发生变化。对于足够薄的壁，我们表明存在瞬时运动学状态，其特征是纵向反射概率（但不是横向模式）。这种效果对扩大早期宇宙的真空气泡的动态具有重要意义。最值得注意的是，它导致了扩展界面的新压力来源，其特征是对气泡壁的$γ$因子的非单调依赖性，并在中间$γ$ factor的峰值达到峰值，我们将其dub最大动态压力。当这种压力足够大以停止气泡壁的加速度时，真空能密度的差异会使一小部分暗光子相对论，从而将它们变成深色辐射。如果深色辐射一直相对论直到迟到，则可以观察到$Δn_\ text {eff} $的可观察贡献，对于具有强度$α\ sim 10^{ - 2} { - 2} -10^{ - 1} $的相变的相变是可能的。
We discuss the dynamics of expanding bubble walls in the presence of massive dark photons whose mass changes as they cross the wall. For sufficiently thin walls, we show that there exists a transient kinematic regime characterized by a constant reflection probability of longitudinal -- but not transverse -- modes. This effect can have important implications for the dynamics of expanding vacuum bubbles in the early Universe. Most notably, it leads to a new source of pressure on the expanding interface, featuring a non-monotonic dependence on the $γ$-factor of the bubble walls and reaching a peak at intermediate $γ$-factors that we dub Maximum Dynamic Pressure. When this pressure is large enough to halt the acceleration of the bubble walls, the difference in vacuum energy densities goes into making a fraction of the dark photons relativistic, turning them into dark radiation. If the dark radiation remains relativistic until late times, an observable contribution to $ΔN_\text{eff}$ is possible for phase transitions with strength $α\sim 10^{-2} - 10^{-1}$.
