标题： 宇宙学一阶相变的能量预算超越袋状方程状态 显示英文标题

标题： The energy budget of cosmological first-order phase transitions beyond the bag equation of state

摘要： 随机引力波背景（SGWBs）来自宇宙学的一阶相变（FOPTs），作为超出粒子物理标准模型的新物理的有希望的探测手段。 当大部分气泡壁在达到终端壁速度后很久相互碰撞时，SGWBs的主要贡献来自于由将释放的真空能量插入整体流体运动的效率因子所表征的声音波。 然而，之前估算这个效率因子的工作只考虑了对称相和破缺相中声速恒定的简化情况，无论是对于声速相等的袋模型还是对于对称相和破缺相中声速不同的$\nu$-模型，从粒子物理的观点来看这是不现实的。 在本文中，我们提出在考虑气泡壁上声速变化的情况下，使用迭代方法求解流体运动方程，针对超越简单袋模型和$\nu$-模型的一般且现实的状态方程（EoS）。 我们发现对整体流体运动效率因子存在抑制效应，尽管在强FOPT情况下这种抑制效应可能可以忽略，此时以前基于袋状态方程对整体流体运动效率因子的估计仍然可以作为一个良好的近似。 显示英文摘要

摘要： The stochastic gravitational-wave backgrounds (SGWBs) from the cosmological first-order phase transitions (FOPTs) serve as a promising probe for the new physics beyond the standard model of particle physics. When most of the bubble walls collide with each other long after they had reached the terminal wall velocity, the dominated contribution to the SGWBs comes from the sound waves characterized by the efficiency factor of inserting the released vacuum energy into the bulk fluid motions. However, the previous works of estimating this efficiency factor have only considered the simplified case of the constant sound velocities in both symmetric and broken phases, either for the bag model with equal sound velocities or $\nu$-model with different sound velocities in the symmetric and broken phases, which is unrealistic from a viewpoint of particle physics. In this paper, we propose to solve the fluid EoM with an iteration method when taking into account the sound-velocity variation across the bubble wall for a general and realistic equation of state (EoS) beyond the simple bag model and $\nu$-model. We have found a suppression effect for the efficiency factor of bulk fluid motions, though such a suppression effect could be negligible for the strong FOPT, in which case the previous estimation from a bag EoS on the efficiency factor of bulk fluid motions still works as a good approximation.