Optimal mean value estimates beyond Vinogradov's mean value theorem

We establish sharp mean value estimates associated with the number of integer solutions of certain systems of diagonal equations. This is the first occasion on which bounds of this quality have been attained for Diophantine systems not of Vinogradov type. As a consequence of this progress, whenever u≥3v we obtain the Hasse principle for systems consisting of v cubic and u quadratic diagonal equations in 6v+4u+1 variables, thus attaining the convexity barrier for this problem.