“…We consider the operator From the mathematical point of view, a reason of interest in potentials of the type Φ( x |x| )/|x| 2s relies in their criticality with respect to the differential operator (−∆) s ; indeed, they have the same homogeneity as the fractional Laplacian (−∆) s , hence they cannot be regarded as a lower order perturbation term. We mention that the operator with singular potentials have been widely studied, see for example [1,13,14,15,17,18,19,20,21,34,36,38,39] and references therein.…”