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arXiv 2408.08951astro-ph.COgr-qchep-ph
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宇宙学准粒子与宇宙学对撞机

Cosmological Quasiparticles and the Cosmological Collider

Jay Hubisz, Seung J. Lee, He Li, Bharath Sambasivam

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31 pages, 11 figures
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AI总结：

本文研究近似共形强耦合理论在暴胀背景中的连续谱与尖锐准粒子峰，预测其在双谱压缩极限中产生可观测的位移振荡信号。

摘要：

宇宙学与强耦合动力学之间的相互作用可产生在晚期消失的瞬态谱特征，但这些特征可能在原初涨落谱中留下唯象信号。尤其引人关注的是具有近似共形不变性的标准模型强耦合扩展。在平直空间中，共形场论中标量算符的谱密度表现为连续谱，其标度律由算符的维数决定，除此之外没有其他结构。AdS/CFT论证表明，对于大N情形，在Hubble率为H的暴胀背景中，该连续谱是有能隙的。我们证明，在参数空间中具有唯象意义的区域内，可能出现额外的峰结构，这些峰会变得尖锐并呈现粒子状；我们还估计了它们对宇宙学可观测量的贡献。我们发现了这些模型所独有、且可能在未来实验中被观测到的现象，包括双谱压缩极限中的位移振荡特征。这些粒子既可以是基本粒子并局域于UV膜，也可以是处于Hubble标度H的复合粒子，并束缚在五维几何体中的视界上。我们还讨论了共形对称性破缺真空的稳定化如何与这些谱特征及其唯象学相关联。

英文摘要：

The interplay between cosmology and strongly coupled dynamics can yield transient spectral features that vanish at late times, but which may leave behind phenomenological signatures in the spectrum of primordial fluctuations. Of particular interest are strongly coupled extensions of the standard model featuring approximate conformal invariance. In flat space, the spectral density for a scalar operator in a conformal field theory is characterized by a continuum with scaling law governed by the dimension of the operator, and is otherwise featureless. AdS/CFT arguments suggest that for large $N$, in an inflationary background with Hubble rate $H$, this continuum is gapped. We demonstrate that there can be additional peak structures that become sharp and particle-like at phenomenologically interesting regions in parameter space, and we estimate their contribution to cosmological observables. We find phenomena that are potentially observable in future experiments that are unique to these models, including displaced oscillatory features in the squeezed limit of the bi-spectrum. These particles can be either fundamental, and localized to a UV brane, or composite at the Hubble scale, $H$, and bound to a horizon in the bulk of the 5D geometry. We comment on how stabilization of conformal symmetry breaking vacua can be correlated with these spectral features and their phenomenology.

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