On the mean square of standard L-functions attached to Ikeda lifts

Abstract

By using estimates on the frequency of large values of the Riemann zetafunction and modular L-functions attached to the full modular group SL(2, Z), we prove sharp upper and lower estimates of the mean square of standard L-functions attached to Siegel cusp forms which are Ikeda lifts, on boundaries and the central line of the critical strip. The mean square of spinor L-functions attached to Saito-Kurokawa lifts is also studied.