On the Stability of the CMC Clifford Tori as Constrained Willmore   Surfaces
  The tori $T_r = r S^1 \times s S^1 \subset S^3$, where $r^2 + s^2 = 1$, are constrained Willmore surfaces, i.e. critical points of the Willmore functional among tori of the same conformal type. We compute which of the $T_r$ are stable critical points. 
Ernst Kuwert, Johannes Lorenz
math.DG