Magnetic Brunn-Minkowski inequalities

We study Minkowski averages on Riemannian manifolds in which the interpolation is by action-minimizing magnetic geodesics with respect to a given magnetic potential. We establish equivalence between Brunn-Minkowski inequalities for this operation and lower bounds on a magnetic Ricci curvature. We then discuss various examples, including natural magnetic fields on K\"ahler and Sasakian manifolds, and prove a sharp, undistorted Brunn-Minkowski inequality for contact magnetic geodesics on the Heisenberg group. We also observe that closed magnetic potentials from different cohomology classes may give rise to different geodesic Minkowski averages.