Comments on $^"$Cosmic evolution in Brans-Dicke chameleon cosmology$^"$

TL;DR

This paper critiques a previous study on cosmic evolution in Brans-Dicke chameleon cosmology, highlighting fundamental issues in their energy conservation and mathematical accuracy that affect their results.

Contribution

The authors identify and clarify errors in a prior work, emphasizing the importance of correct methods in scalar-tensor gravity models.

Findings

Incorrect energy conservation equation in the previous work

Mathematical mistakes lead to different results

Highlights proper method for deriving conservation equations

Abstract

The authors of Ref. \cite{1-2}, investigated cosmic evolution in an external interacting model of scalar tensor gravity namely Brans Dicke chameleon scenario. The procedure of this work contains novelties but, it shall be observed from this comment, their report faces three fundamental drawbacks. One of them concerns the energy conservation equation, and the other two flaws are about mathematical mistakes. In the scalar tensor gravity models, a well-known method, in order to obtain conservation equation one must combine Friedmann equations with modified Klein-Gordon equation. But in Ref. \cite{1-2}, by virtue of the mentioned approach one would not be able to achieve a correct result for conservation equation. In addition, one can readily realize that their mathematical mistakes lead to different results compared to the present report.