One-parameter family of indecomposable optimal entanglement witnesses arising from generalized Choi maps

In a recent paper [D. Chruscinski and F. A. Wudarski, Open Sys. Information Dyn. (unpublished)], it was conjectured that the entanglement witnesses arising from some generalized Choi maps are optimal. We show that this conjecture is true. Furthermore, we show that they provide a one-parameter family of indecomposable optimal entanglement witnesses.