Many problems that are claimed to be convex in papers are not in fact written in their solvable form in those same papers. I wish authors would be required to be more explicit in showing exactly how they solved problems they claim are convex. Heck, if they claim to use CVX they should include the model code or make it readily available, but they often do not.
But I can’t blame authors for the failure of CVX users to read and obey the FAQ. Have you proven it is convex yet? It is not enough to trust other papers. You must prove it is convex, yourself. And more importantly, you must be able to do it solely by using only the rules laid out in the DCP ruleset, using the functions found in the supported function list.
The very fact that you asked “How to divide real affine matrix by real affine scalar” tells me you haven’t followed those instructions. You would not have asked this if you had, because the DCP rules clearly do not allow this, and the FAQ explains why. The same goes for your attempt to subtract one concave logarithm from another.