标题： 早期引力波对双引力理论的温和限制 显示英文标题

标题： Mild bounds on bigravity from primordial gravitational waves

摘要： 如果近期能够测量原初引力波的振幅，它能告诉我们什么关于双引力理论的信息？ 为了解决这个问题，我们通过关注参数空间中的一个安全区域来研究具有质量的双引力理论，该区域避免了已知的不稳定性。 类似于晚期时间约束的研究，我们隐含地假设存在Vainshtein机制的成功实现，这保证了标准宇宙学演化基本不受影响。 我们发现，可行的双引力模型受到的限制比具有质量的引力理论要宽松得多，在后者中只有一组（具有质量的）张量模式。 原则上，这种理论对重新结合时期的有效引力子质量敏感，但我们发现在我们的设定下，原初张量谱对无质量张量部分的动力学反应更强烈，而非其有质量的对应部分。 我们进一步表明，该理论的参数空间中存在一些有趣窗口，这些窗口可能在B模谱中诱导出独特的特征信号。 显示英文摘要

摘要： If the amplitude of primordial gravitational waves is measured in the near-future, what could it tell us about bigravity? To address this question, we study massive bigravity theories by focusing on a region in parameter space which is safe from known instabilities. Similarly to investigations on late time constraints, we implicitly assume there is a successful implementation of the Vainshtein mechanism which guarantees that standard cosmological evolution is largely unaffected. We find that viable bigravity models are subject to far less stringent constraints than massive gravity, where there is only one set of (massive) tensor modes. In principle sensitive to the effective graviton mass at the time of recombination, we find that in our setup the primordial tensor spectrum is more responsive to the dynamics of the massless tensor sector rather than its massive counterpart. We further show there are intriguing windows in the parameter space of the theory which could potentially induce distinctive signatures in the B-modes spectrum.