论文标题
大和负熵质量的通货膨胀模型中的非高斯
Non-Gaussianities in models of inflation with large and negative entropic masses
论文作者
论文摘要
熵方向的通货膨胀模型$ | m_s | \ gg h $可以通过具有虚速$ C_S $的单场EFT来很好地描述。除其他功能外，他们还预测了标量扰动频谱的指数增强，但是非高斯均未遗传。在这项工作中，我通过考虑接触相互作用和交换图的贡献来完成此EFT中三光谱的计算。虽然对于大多数形状而言，三角光谱大约是恒定的，但我发现，对于某些配置，所有动量都崩溃到一行，三角镜与触点交互的$（m_s/h）^5 $成正比，以及以前的工作所预期的交换图。我还讨论了结果的紫外线敏感性，并论证了为什么EFT提供了良好的数量级估计。最后，我面对标量频谱对观察的不同预测。在熵质量与慢速参数$ε$的正功率成正比的模型中，就像在过度通货膨胀中一样，光谱在小尺度上生长，并受到原始黑洞过多生产的限制。以正确的幅度和频谱倾斜在CMB尺度上共同施加这种约束，排除了大量电势。只有那些由$m_sδ/h \ sim {\ cal o}（-0.01）$控制的光谱倾斜的那些，其中$δ= \dotε/（εh）$是第二个慢速参数，可能是观察性的。最后，Biseptrum上的约束通常强加了$ | c_s m_s |/h \ lyseSim 10-20 $，而Trispectrum上的那些则在使用$ G_ \ text {nl}^{nl}^{\dotσ^4} $上的约束时会产生较弱的界限。对于过膨胀，双光谱结合转化为$ω\ Lessim 11 $，其中$ω$是场空间的转盘率。
Models of inflation where the entropic directions have large and negative masses $|m_s| \gg H$ can be well described by a single-field EFT with an imaginary sound speed $c_s$. Among other features, they predict an exponential enhancement of the spectrum of scalar perturbations which however is not inherited by non-Gaussianities. In this work, I complete the calculation of the trispectrum in this EFT by considering the contributions from the contact interaction and the exchange diagram. While for most shapes the trispectrum is approximately constant, I find that for certain configurations where all the momenta collapse to a line the trispectrum is proportional to $(m_s/H)^5$ for the contact interaction and to $(m_s/H)^6$ for the exchange diagram, as anticipated by previous work. I also discuss the UV sensitivity of the results and argue why the EFT provides a good order of magnitude estimate. In the end, I confront the different predictions for the scalar spectrum against observations. In models where the entropic mass is proportional to a positive power of the slow-roll parameter $ε$, like in hyperinflation, the spectrum grows on small scales and becomes constrained by the overproduction of primordial black holes. Imposing such constraint jointly with the correct amplitude and spectral tilt at CMB scales excludes a large set of potentials. Only those where the spectral tilt is controlled by $m_s δ/H \sim {\cal O}(-0.01)$, where $δ=\dotε/(εH)$ is the second slow-roll parameter, are likely observationally viable. Finally, the constraints on the bispectrum generically impose $|c_s m_s|/H \lesssim 10-20$ while those on the trispectrum give a weaker bound when using the constraints on $g_\text{NL}^{\dotσ^4}$ as a proxy. For hyperinflation the bispectrum bound translates into $ω\lesssim 11$ where $ω$ is the turning rate in field-space.
