论文标题
MoiréGravityand Gosmology
Moiré Gravity and Cosmology
论文作者
论文摘要
真空灾难是一个基本的难题，其中观察到的宇宙常数尺度比理论中预期的自然尺度小的数量级。这项工作提出了一种新的“双世界”结构，该结构可能可以洞悉宇宙学不变问题。该模型通常包括$（3+1）$ - 维歧管，上面有两个不同的几何和物质字段。与重力理论（经典）和真空限制相反，该模型减少到两种无质量的重力理论，从而不含鬼魂。差异不变性和因果关系高度限制了两个指标与合成相关的，$η_{μν} = ϕ^2 g_ {μν} $。这将理论降低到了标准的单个世界描述中，但引入了一种固有的几何“moiré领域”，即$ ϕ $。有趣的是，Moiré领域具有传统理论中熟悉的Dilaton和Higgs领域的特征。整合Moiré领域自然会引起Starobinsky的动作和通货膨胀动态。在Friedmann-Lemaitre-Robertson-Walker解决方案的框架内，我们将Moiré场的有效作用降低到墨西哥帽子潜力的粒子的有效作用。然后，进行运动方程式，并显示了Moiré场以振荡方式接近墨西哥帽的最小值，并伴随着哈勃参数的衰减。在其他合理的假设下，真空能在通货膨胀进化结束时渐近地接近零。这里提出的物理学与凝聚态和其他地方的Moiré现象具有相似之处，与天然理论相比，两个相似的结构叠加到具有低新兴能量尺度的上部结构。
The vacuum catastrophe is a fundamental puzzle, where the observed scales of the cosmological constant are many orders of magnitude smaller than the natural scales expected in the theory. This work proposes a new "bi-world" construction that may offer an insight into the cosmological constant problem. The model generally includes a $(3+1)$-dimensional manifold with two different geometries and matter fields residing on them. In contrast to bimetric or massive theories of gravity, classically, and in the vacuum limit, the model reduces to two massless gravity theories, thereby living ghost-free. The diffeomorphism invariance and causality highly constrain the two metrics to be conformally related, $η_{μν} = ϕ^2 g_{μν}$. This reduces the theory to a standard single-world description, but introduces a new inherently geometrical "moiré field," $ϕ$. Interestingly, the moiré field has the character of both a dilaton and Higgs field familiar in the conventional theory. Integrating out the moiré field naturally gives rise to the Starobinsky action and inflationary dynamics. In the framework of the Friedmann-Lemaitre-Robertson-Walker solution, we reduce an effective action for the moiré field to that of a particle moving in a Mexican hat potential. The equations of motion are then solved numerically and the moiré field is shown to approach a Mexican-hat minimum in an oscillatory fashion, which is accompanied by the decay of the Hubble parameter. Under additional reasonable assumptions, the vacuum energy asymptotically approaches zero in the end of inflationary evolution. The physics presented here shares similarities with the moiré phenomena in condensed matter and elsewhere, where two similar structures superimposed upon give rise to a superstructure with low emergent energy scales compared to the native theories.
