Bootstrapping large graviton non-Gaussianities
Bootstrapping large graviton non-Gaussianities
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DOI：
10.1007/jhep05(2022)077
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发表时间：
2021-09
影响因子：
5.4
通讯作者：
G. Cabass;E. Pajer;David Stefanyszyn;Jakub Supeł
中科院分区：
文献类型：
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作者：
G. Cabass;E. Pajer;David Stefanyszyn;Jakub Supeł
引力干涉仪和宇宙微波背景的宇宙学观测为我们探索原始宇宙中的引力定律提供了前景。为了研究和解释这些数据集，我们需要知道可能的引力子非高斯性。为此，我们在假设尺度不变的情况下，推导出无质量引力子所有阶导数的最一般的树级三点函数（双谱）。我们没有使用显式拉格朗日量，而是采用自举方法，并使用最近从统一性、局部性和真空选择中得到的约束来获得我们的结果。由于我们没有对德西特推进做任何假设，我们的结果捕捉到了大量模型的现象学，比如膨胀的有效场论和固体膨胀。给出了无限个偶偶偶双谱的计算公式。值得注意的是，对于奇偶双谱，我们证明了唯一性只允许少数几种可能的形状：引力子-引力子-引力子有三种，标量-引力子-引力子有三种，标量-标量-引力子有一种，我们明确地自举了这些形状。这些奇偶非高斯性可能很大，例如在固体膨胀中，因此构成了未来观测的具体和良好动机的目标。
Gravitational interferometers and cosmological observations of the cosmic microwave background offer us the prospect to probe the laws of gravity in the primordial universe. To study and interpret these datasets we need to know the possible graviton non-Gaussianities. To this end, we derive the most general tree-level three-point functions (bispectra) for a massless graviton to all orders in derivatives, assuming scale invariance. Instead of working with explicit Lagrangians, we take a bootstrap approach and obtain our results using the recently derived constraints from unitarity, locality and the choice of vacuum. Since we make no assumptions about de Sitter boosts, our results capture the phenomenology of large classes of models such as the effective field theory of inflation and solid inflation. We present formulae for the infinite number of parity-even bispectra. Remarkably, for parity-odd bispectra, we show that unitarity allows for only a handful of possible shapes: three for graviton-graviton-graviton, three for scalar-graviton-graviton and one for scalar-scalar-graviton, which we bootstrap explicitly. These parity-odd non-Gaussianities can be large, for example in solid inflation, and therefore constitute a concrete and well-motivated target for future observations.