Hard analysis meets critical knots (Stationary points of the Moebius   energy are smooth)
  We prove that if a curve parametrized by arc length is a stationary point of the Moebius energy introduced by Jun O'Hara, then it is smooth whenever the Moebius energy is finite. Our methods, interestingly, only rely on purely analytical arguments, entirely without using Moebius invariance. Furthermore, the techniques involved are not fundamentally restricted to one-dimensional domains, but are generalizable to arbitrary dimensions. 
Simon Blatt, Philipp Reiter, Armin Schikorra
math.AP