The mirror quintic as a quintic

Abstract

The general quintic hypersurface in ${\mathbb P}^4$ is the most famous example of a Calabi--Yau threefold for which mirror symmetry has been investigated in detail. There is a description of the mirror as a hypersurface in a certain weighted projective space. In this note we present a model for the mirror which is again (the resolution of) a quintic hypersurface in ${\mathbb P}^4$. We also deal with the special members in the respective families. They lead to rigid Calabi--Yau threefolds with interesting arithmetical properties. In the last section we try to find a similarly nice model for the mirror of the complete intersection of two cubics in ${\mathbb P}^5$. We also formulate a general question about mirror models.