The objective function is not concave, so the problem is not convex, so not solvable by CVX. Actually, I believe the objective function is convex over the domain in your constraints.
If it can be handled by CVXPY at all, it would not be in the DCP mode. Perhaps it can be handled (with no assurance of finding global optimum) by DCCP, but that is out of scope of CVX and the CVX forum.
Please read
Why isn't CVX accepting my model? READ THIS FIRST! .
That will help you for CVX and CVXPY, although CVXPY does have some additoonal capabilities which CVX does not, such as DCCP.