The arithmetic de Rham stack

We define and study the arithmetic de Rham stack $X^{\mathrm{arith}}$ of a scheme $X$ over a field of characteristic $p$, and analyze its relation with related stacks such as the Hyodo–Kato stack. We show that $X^{\mathrm{arith}}$ gives a stack-theoretic approach to rigid cohomology and its coefficients, known as overconvergent isocrystals and arithmetic $D$-modules, which avoids the long-standing problem of frame-choosing in earlier approaches. We finally give some arithmetic applications of our formalism, such as a proof of Berthelot’s conjecture on the preservation of overconvergent isocrystals by smooth proper pushforward.