Title: Fundamental solutions for second order parabolic systems with drift terms,
Abstract: We construct fundamental solutions of second-order parabolic systems of
divergence form with bounded and measurable leading coefficients and divergence
free first-order coefficients in the class of $BMO^{-1}_x$, under the
assumption that weak solutions of the system satisfy a certain local
boundedness estimate. We also establish Gaussian upper bound for such
fundamental solutions under the same conditions.