Abstract:
Cactus group is the fundamental group of the real locus of the Deligne-
Mumford moduli space of stable rational curves. We define an action of
this group on the set of Bethe vectors of the Gaudin magnet chain (for Lie
algebra $\mathfrak{sl}(2)$) and relate this to the Berenstein-Kirillov group of piecewise
linear transformations of the Gelfand-Tsetlin polytope. Some conjectures
generalizing this construction will be discussed.