Tests of the gravitational inverse-square law below the dark-energy length scale

We conducted three torsion-balance experiments to test the gravitational inverse-square law at separations between 9.53 mm and 55 mu m, probing distances less than the dark-energy length scale lambda(d) = (4)root hc/rho(d) approximate to 85 mu m. We find with 95% confidence that the inverse-square law holds (vertical bar alpha vertical bar <= 1) down to a length scale lambda=56 mu m and that an extra dimension must have a size R <= 44 mu m.