“…Recently there are also a few works concerning on gradient perturbations and Schrödinger perturbations of fractional Laplacian (see e.g. [9,10,11,12,15,16,25,27,28,33,34]). In particular, according to [33,Theorem 3.4], when the potential belongs to the so-called Kato class, heat kernel estimates for Schrödinger perturbations of fractional Laplacian are comparable with these for fractional Laplacian (at least for any fixed finite time).…”