Recovering nonsmooth coefficients for higher-order perturbations of a polyharmonic operator

Abstract We consider an inverse problem for a higher order elliptic operator where the principal part is the 
polyharmonic operator $(-\Delta)^m$ with $ m \geq 2$. We show that the map from the coefficients to a 
certain bilinear form is injective. We have a particular focus on obtaining these results under lower
regularity on the coefficients. It is known that knowledge of this bilinear form is equivalent to a knowledge of 
a Dirichlet to Neumann map or the Cauchy data for solutions.