论文标题
修饰的重力中的曲率耦合：从线性模型到共同不变理论
Curvature-matter couplings in modified gravity: from linear models to conformally invariant theories
论文作者
论文摘要
在此程序中，我们回顾了重力理论，并在标量曲率的任意函数和物质的拉格朗日密度之间建立了曲率 - 物体耦合。这种显式的非最小耦合诱导了能量弹药张量的非逐渐变化的协变量，这意味着非晶格运动，因此导致了额外力的出现。在这里，我们通过在存在物质创造/歼灭的情况下利用开放系统不可逆的热力学的形式形式来探讨能量弹药张量的非传播的物理和宇宙学含义。粒子的产生速率，压力和共同熵的表达是以协变量公式获得的，并详细讨论。开放系统的热力学与引力场方程一起应用，导致标准$λ$ CDM宇宙学范式的概括，其中粒子的产生速率和压力被有效地视为宇宙学流体能量量的组成部分。此外，我们还简要介绍了曲率与几何形状的耦合，通过假设形式$ l_m \ tilde {r}^2 $的耦合术语，其中$ l_m $，其中$ l_m $是普通的lagrangian，是普通的lagrangian，$ \ \ tilde {r} r} $是weyl salcar。耦合明确满足了理论的形式不变性的要求。 Expressing $\tilde{R}^2$ with the use of an auxiliary scalar field and of the Weyl scalar, the gravitational action can be linearized in the Ricci scalar, leading in the Riemann space to a conformally invariant $f\left(R,L_m\right)$ type theory, with the matter Lagrangian nonminimally coupled to geometry.
In this proceeding, we review modified theories of gravity with a curvature-matter coupling between an arbitrary function of the scalar curvature and the Lagrangian density of matter. This explicit nonminimal coupling induces a non-vanishing covariant derivative of the energy-momentum tensor, that implies non-geodesic motion and consequently leads to the appearance of an extra force. Here, we explore the physical and cosmological implications of the nonconservation of the energy-momentum tensor by using the formalism of irreversible thermodynamics of open systems in the presence of matter creation/annihilation. The particle creation rates, pressure, and the expression of the comoving entropy are obtained in a covariant formulation and discussed in detail. Applied together with the gravitational field equations, the thermodynamics of open systems lead to a generalization of the standard $Λ$CDM cosmological paradigm, in which the particle creation rates and pressures are effectively considered as components of the cosmological fluid energy-momentum tensor. Furthermore, we also briefly present the coupling of curvature to geometry in conformal quadratic Weyl gravity, by assuming a coupling term of the form $L_m\tilde{R}^2$, where $L_m$ is the ordinary matter Lagrangian, and $\tilde{R}$ is the Weyl scalar. The coupling explicitly satisfies the requirement of the conformal invariance of the theory. Expressing $\tilde{R}^2$ with the use of an auxiliary scalar field and of the Weyl scalar, the gravitational action can be linearized in the Ricci scalar, leading in the Riemann space to a conformally invariant $f\left(R,L_m\right)$ type theory, with the matter Lagrangian nonminimally coupled to geometry.
