标题： 链式暴胀的引力波谱 显示英文标题

标题： The Gravitational Wave Spectrum of Chain Inflation

摘要： 链式膨胀是慢滚膨胀的一种替代方案，其中暴胀场沿着其势能中的大量连续极小值进行量子隧穿。 在本工作中，我们首次对链式膨胀的引力波谱进行了全面计算。 与慢滚膨胀不同，后者并非源自暴胀期间引力场的量子涨落，而是源自与真空中隧穿相关的第一性相变期间的气泡碰撞。 我们的计算是在一个有效的链式膨胀理论框架内进行的，该理论基于对隧穿率的展开，涵盖了大部分可用的模型空间。 有效理论可被视为链式膨胀在滚动模型中的慢滚展开类比。 我们表明，链式膨胀会产生非常特征性的双峰谱：一个微弱的高频峰与暴胀期间发出的引力辐射有关，一个强烈的低频峰与链式膨胀的平滑退出有关（标志着向辐射主导时代过渡）。 在aLIGO-aVIRGO-KAGRA网络、LISA和/或脉冲星计时阵列实验中，存在非常令人兴奋的前景来检验来自链式膨胀的引力波信号。 我们指出的一个特别引人注目的可能性是，链式膨胀可能是最近由NANOGrav、PPTA、EPTA和CPTA检测到的随机引力波背景的来源。 我们还表明，链式膨胀的引力波信号通常伴随着标量谱指数的运行/更高阶运行，这些可以在未来的宇宙微波背景实验中进行测试。 显示英文摘要

摘要： Chain inflation is an alternative to slow-roll inflation in which the inflaton tunnels along a large number of consecutive minima in its potential. In this work we perform the first comprehensive calculation of the gravitational wave spectrum of chain inflation. In contrast to slow-roll inflation the latter does not stem from quantum fluctuations of the gravitational field during inflation, but rather from the bubble collisions during the first-order phase transitions associated with vacuum tunneling. Our calculation is performed within an effective theory of chain inflation which builds on an expansion of the tunneling rate capturing most of the available model space. The effective theory can be seen as chain inflation's analogue of the slow-roll expansion in rolling models of inflation. We show that chain inflation produces a very characteristic double-peak spectrum: a faint high-frequency peak associated with the gravitational radiation emitted during inflation, and a strong low-frequency peak associated with the graceful exit from chain inflation (marking the transition to the radiation-dominated epoch). There exist very exciting prospects to test the gravitational wave signal from chain inflation at the aLIGO-aVIRGO-KAGRA network, at LISA and /or at pulsar timing array experiments. A particularly intriguing possibility we point out is that chain inflation could be the source of the stochastic gravitational wave background recently detected by NANOGrav, PPTA, EPTA and CPTA. We also show that the gravitational wave signal of chain inflation is often accompanied by running/ higher running of the scalar spectral index to be tested at future Cosmic Microwave Background experiments.