论文标题
在rastall重力公式上，作为$ f（r，\ mathcal {l} _m）$和a $ f（r，t）$理论
On Rastall gravity formulation as a $f(R,\mathcal{L}_m)$ and a $f(R,T)$ theory
论文作者
论文摘要
Rastall引入了一种应力能量张量，其差异与RICCI标量的梯度成正比。该提议导致了一般相对性的场方程形式的变化，但它保留了自由度的数量。 Rastall的场方程可以用重新定义的集合解释为GR，也可以暗示物质部门内部的物理后果。我们调查了可以直接从操作派生的rastall场方程的限制，尤其是从两个$ f（r）$ - 重力扩展名：$ f（r，\ mathcal l_m）$和$ f（r，t）$。我们表明，这些理论之间存在相似之处，但是除了这里讨论的某些特定情况外，Rastall集无法完全从中恢复。值得注意的是，正如Rastall提出的那样，该集合的简单，协变和可逆的重新定义很难在动作中直接实施。
Rastall introduced a stress-energy tensor whose divergence is proportional to the gradient of the Ricci scalar. This proposal leads to a change in the form of the field equations of General Relativity, but it preserves the number of degrees of freedom. Rastall's field equations can be either interpreted as GR with a redefined SET, or it can imply different physical consequences inside the matter sector. We investigate limits under which the Rastall field equations can be directly derived from an action, in particular from two $f(R)$-gravity extensions: $f(R,\mathcal L_m)$ and $f(R,T)$. We show that there are similarities between these theories, but the Rastall SET cannot be fully recovered from them, apart from certain particular cases here discussed. It is remarkable that a simple, covariant and invertible redefinition of the SET, as the one proposed by Rastall, is hard to be directly implemented in the action.
