Correlations of the squares of the Riemann zeta function on the critical line

Abstract

We compute the average of a product of two shifted squares of the Riemann zeta function on the critical line with shifts up to size $T^{3/2-\epsilon }$. We give an explicit expression for such an average and derive an approximate spectral expansion for the error term similar to Motohashi's. As a consequence, we also compute the (2,2)-moment of moment of the Riemann zeta function, for which we partially verify (and partially refute) a conjecture of Bailey and Keating.