论文标题

palatini的形式的形式不变的$ f \ left(r,l_m \ right)$重力理论

Palatini formulation of the conformally invariant $f\left(R, L_m\right)$ gravity theory

论文作者

Harko, Tiberiu, Shahidi, Shahab

论文摘要

我们通过使用palatini形式主义研究了与曲率 - 曲率耦合的同形重力模型的场方程,并使用曲率 - 曲率耦合。我们考虑通过与Weyl载体相关的场的强度以及由物质Lagrangian和Weyl标量构建的,由与Weyl Vector相关的场的强度,与Weyl Vector相关的场的强度以及共同不变的几何形状耦合项给出的情况的情况。在用riemannian对应物来代替Weyl标量后,二次作用是在Riemann几何形状中定义的,并涉及RICCI标量与物质Lagrangian之间的非微小耦合。为了普遍性,还考虑了一个更一般的拉格朗日,其中Weyl Vector与RICCI标量的任意功能无关紧要。通过独立于指标和连接而改变动作,独立的连接可以表示为辅助,RICCI标量和Weyl vector依赖度量的LEVI-CIVITA连接,这是通过共生转换与物理度量有关的。在公制和palatini公式中获得了场方程。针对与不同形式的耦合函数相对应的三种不同模型,研究了palatini场方程的宇宙学含义。还进行了与标准$λ$ CDM模型的比较,我们发现Palatini型宇宙学模型可以对观测值提供可接受的描述。

We investigate the field equations of the conformally invariant models of gravity with curvature-matter coupling, constructed in Weyl geometry, by using the Palatini formalism. We consider the case in which the Lagrangian is given by the sum of the square of the Weyl scalar, of the strength of the field associated to the Weyl vector, and a conformally invariant geometry-matter coupling term, constructed from the matter Lagrangian and the Weyl scalar. After substituting the Weyl scalar in terms of its Riemannian counterpart, the quadratic action is defined in Riemann geometry, and involves a nonminimal coupling between the Ricci scalar and the matter Lagrangian. For the sake of generality, a more general Lagrangian, in which the Weyl vector is nonminmally coupled with an arbitrary function of the Ricci scalar, is also considered. By varying the action independently with respect to the metric and the connection, the independent connection can be expressed as the Levi-Civita connection of an auxiliary, Ricci scalar and Weyl vector dependent metric, which is related to the physical metric by means of a conformal transformation. The field equations are obtained in both the metric and the Palatini formulations. The cosmological implications of the Palatini field equations are investigated for three distinct models corresponding to different forms of the coupling functions. A comparison with the standard $Λ$CDM model is also performed, and we find that the Palatini type cosmological models can give an acceptable description of the observations.

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