On the lifting of hermitian modular forms

Abstract

AbstractLet K be an imaginary quadratic field with discriminant −D. We denote by 𝒪 the ring of integers of K. Let χ be the primitive Dirichlet character corresponding to K/ℚ. Let $\Gamma ^{(m)}_K=\mathrm {U} (m,m)({\mathbb Q})\cap \mathrm {GL}_{2m}({\cal O})$ be the hermitian modular group of degree m. We construct a lifting from S2k(SL2(ℤ)) to S2k+2n(ΓK(2n+1),det −k−n) and a lifting from S2k+1(Γ0(D),χ) to S2k+2n(ΓK(2n),det −k−n). We give an explicit Fourier coefficient formula of the lifting. This is a generalization of the Maass lift considered by Kojima, Krieg and Sugano. We also discuss its extension to the adele group of U(m,m).