On the standard models of del Pezzo fibrations of degree four

Abstract: Corti defined the notion of standard models of del Pezzo fibrations, and studied their existence over $\mathbb{C}$ with a fixed generic fibre. In this paper, we prove the existence of standard models of del Pezzo fibrations of degree $4$ in characteristic $>2$. To show this, we use the notion of Koll\'ar stability, which was introduced by Koll\'ar and Abban-Fedorchuk-Krylov.