标题： 原始黑洞来自一个中断的相变 显示英文标题

标题： Primordial black holes from an interrupted phase transition

摘要： 我们提出了一种新的原始黑洞形成机制，通过膨胀后重新加热早期物质主导阶段中的中断相变来实现。在由无压流体（通胀末期主导宇宙的流体，称为重新加热子）衰变引起的重新加热过程中，辐射浴的温度通常会增加，达到最大温度 $T_{\rm max}$，然后下降。我们考虑一种由温度升高诱导的一阶相变，但由于 $T_{\rm max}$ 高于临界温度但不足以克服宇宙膨胀使得气泡成核率超过宇宙膨胀速度，因此该相变被中止。尽管气泡从未完全占据空间，但仍有一些可能会成核并扩张，直到温度再次下降到临界温度。我们论证了这些气泡在温度进一步降低时会收缩并消失，留下具有正密度扰动的宏观球形区域。这些扰动区域会吸收周围的物质（重新加热子），最终坍缩成原始黑洞，其质量会继续增长直至辐射主导阶段开始。我们根据 $T_{\rm max}$ 处的气泡成核率估计了这些原始黑洞的丰度，并表明从现象学角度来看，这种丰度可能相当大。 显示英文摘要

摘要： We propose a new mechanism of primordial black hole formation via an interrupted phase transition during the early matter-dominated stage of reheating after inflation. In reheating, induced by the decay of a pressureless fluid dominating the Universe at the end of inflation, dubbed as reheaton, the temperature of the radiation bath typically increases, reaching a maximum temperature $T_{\rm max}$, and then decreases. We consider a first-order phase transition induced by the increase of the temperature that is aborted as $T_{\rm max}$ is higher than the critical temperature but not sufficiently high for the bubble nucleation rate to overcome the expansion of the Universe. Although bubbles never fully occupy the space, some may be nucleated and expand until the temperature once again decreases to the critical temperature. We argue that these bubbles shrink and disappear as the temperature drops further, leaving behind macroscopic spherical regions with positive density perturbations. These perturbed regions accrete the surrounding matter (reheatons) and eventually collapse into primordial black holes whose mass continues to grow until the onset of radiation domination. We estimate the abundance of these primordial black holes in terms of the bubble nucleation rate at $T_{\rm max}$, and demonstrate that the abundance can be significantly large from a phenomenological perspective.