On parabolic equations with singular drift in Sobolev-Morrey spaces with mixed norms in unusual order

We present an existence and uniqueness theorem for parabolic equations with singular drift in the whole space in Sobolev-Morrey function spaces in which with mixed norms are used when the inside integration is performed with respect to t. Some techniques leading to the proof will be discussed. They are based on the Fefferman-Stein theorem, the Hardy-Littlewood theorem, Muckenhoupt weights, the Rubio de Francia extrapolation theorem, and the Dong-Kim mixed norm theorem.
References
[1] Essentials of Real Analysis and Morrey-Sobolev spaces for second-order elliptic and parabolic PDEs with singular first-order coefficients, arxiv:2505.14863