Metric-affine gravity and inflation
Metric-affine gravity and inflation
复制标题
DOI：
10.1103/physrevd.99.104020
复制
发表时间：
2018-12
影响因子：
5
通讯作者：
K. Shimada;K. Aoki;K. Maeda
中科院分区：
文献类型：
--
作者：
K. Shimada;K. Aoki;K. Maeda
我们对度规-仿射引力理论进行了分类，其中度规和连接被视为独立的变量，利用了对连接的几个约束。假设爱因斯坦-希尔伯特作用，我们发现畸变张量（扭转和非度规）的方程变成代数的，这意味着这些变量不是动态的。因此，我们可以用黎曼几何的形式重写基本方程。虽然所有的分类模型都恢复了Palatini形式下的爱因斯坦引力（其中我们假设物质与连接之间没有耦合），但是当物质场与连接耦合时，有效的爱因斯坦方程包括一个额外的从畸变张量获得的超能量动量张量。假设一个最小耦合标量场在度量-仿射引力中的简单扩展，我们分析了一个暴胀情景。即使我们采用混沌暴胀势，某些参数也可以满足观测约束。此外，我们还发现了度量仿射中伽利略标量场的一种简单形式可以引起g暴胀。
We classify the metric-affine theories of gravitation, in which the metric and the connections are treated as independent variables, by use of several constraints on the connections. Assuming the Einstein-Hilbert action, we find that the equations for the distortion tensor (torsion and non-metricity) become algebraic, which means that those variables are not dynamical. As a result, we can rewrite the basic equations in the form of Riemannian geometry. Although all classified models recover the Einstein gravity in the Palatini formalism (in which we assume there is no coupling between matter and the connections), but when matter field couples to the connections, the effective Einstein equations include an additional hyper energy-momentum tensor obtained from the distortion tensor. Assuming a simple extension of a minimally coupled scalar field in metric-affine gravity, we analyze an inflationary scenario. Even if we adopt a chaotic inflation potential, certain parameters could satisfy observational constraints. Furthermore, we find that a simple form of Galileon scalar field in metric-affine could cause G-inflation.