We consider Kolmogorov operator $$-\nabla \cdot a \nabla + b $$ with measurable uniformly elliptic matrix and prove Gaussian lower upper bounds on its heat kernel under minimal assumptions the vector field divergence $$\mathrm{div\,}b$$ . More precisely, we prove: (1) bound, provided that $$\mathrm{div\,}b \ge 0$$ , is in class of form-bounded fields (containing e.g. $$L^d$$ weak class, as well...