On Zeta Functions Associated to the Product of Two Eisenstein Series

Let E(z, s) be the Eisenstein series for the full modular group Γ, and let Δ = y 2 ( ∂ 2 ∂ x 2 + ∂ 2 ∂ y 2 ) https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780203747018/bef25d74-ef02-4914-ac4f-27ec89fc30ac/content/eq942.tif"/>