On Galois representations via Siegel modular forms of genus two (Q5953011)

The authors study four-dimensional Galois representations attached to Siegel modular forms. They determine many cases where projective symplectic groups occur as Galois groups over \(\mathbb{Q}\), a result closed to the classical one of Deligne, concerning usual modular forms and two \(l\)-adic representations of the absolute Galois group of \(\mathbb{Q}\). The paper also contains interesting explicit calculations, especially of eigenvalues for Hecke operators.