The Mukai conjecture via Cox rings for special toric ambient embeddings

Abstract

We prove the Mukai conjecture on the characterisation of products of projective spaces among Fano varieties for a class of locally factorial Fano varieties defined in terms of their Cox rings. The Fano varieties of this class are characterised in terms of the property that they admit an embedding into a smooth projective toric variety via the bunched ring theory of Mori dream spaces. Our approach inherits the Mukai conjecture for this class from a log version of the Mukai conjecture on the toric ambient embedding.