Abstract
Let X = G/Gamma, where G is a Lie group and Gamma is a lattice in G, and let U be a subset of X whose complement is compact. We use the exponential mixing results for diagonalizable flows on X to give upper estimates for the Hausdorff dimension of the set of points whose trajectories miss U. This extends a recent result of Kadyrov et al. (Dyn Syst 30(2):149-157, 2015) and produces new applications to Diophantine approximation, such as an upper bound for the Hausdorff dimension of the set of weighted uniformly badly approximable systems of linear forms, generalizing an estimate due to Broderick and Kleinbock (Int J Number Theory 11(7):2037-2054, 2015).