On the Willmore energy of M\"{o}bius bands
We show that among M\"obius bands in $\mathbb{S}^3$ bounded by a great circle, the minimal Willmore energy is realized by an embedded minimal M\"obius band with Morse index two. To prove this, we introduce a $2$-parameter ``canonical family"associated to any non-orientable surface in $\mathbb{S}^3$ with boundary a grea...