2015/06/30 by Lamm, Tobias, Schätzle, Reiner M.
#Analysis of PDEs (math.AP) #Differential Geometry (math.DG) #FOS: Mathematics
paper · doi:10.48550/arxiv.1506.09154
For every two-dimensional torus T2 and every k∈ ℕ, k≥ 3, we construct a conformal Willmore immersion f:T2→ ℝ4 with exactly one point of density k and Willmore energy 4πk. Moreover, we show that the energy value 8π cannot be attained by such an immersion. Additionally, we characterize the branched double covers T2→ S2 × \0\ as the only branched conformal immersions, up to Möbius transformations of ℝ4, from a torus into ℝ4 with at least one branch point and Willmore energy 8π. Using a perturbation argument in order to regularize a branched double cover, we finally show that the infimum of the Willmore energy in every conformal class of tori is less than or equal to 8π.