Deformations and Lifts of Calabi-Yau Varieties in Characteristic p

We study deformations of Calabi-Yau varieties in characteristic p using techniques from derived algebraic geometry. We prove a mixed characteristic analogue of the Bogomolov-Tian-Todorov theorem (which states that Calabi-Yau varieties in characteristic 0 are unobstructed), and we show that ordinary Calabi-Yau varieties admit canonical lifts to characteristic 0, generalising the Serre-Tate theorem on ordinary abelian varieties.