L^(p,q) estimates on the transport density

In this paper, we show a new regularity result on the transport density {\sigma} in the classical Monge-Kantorovich optimal mass transport problem between two measures, {\mu} and {\nu}, having some summable densities, f^+ and f^-. More precisely, we prove that the transport density {\sigma} belongs to L^{p,q}({\Omega}) as soon as f^+, f^- \in L^{p,q}({\Omega}).