查看文章

It is known via work of Duke and Ghate that there are only finitely many pairs of full level, degree one eigenforms f and g whose product fg is also an eigenform. We prove a partial generalization of this theorem for degree two Siegel modular forms. Namely, we show that there is only one pair of eigenforms F and G such that FG is a non-cuspidal eigenform. In the case that FG is a cuspform, we provide necessary conditions for FG to be an eigenform, give one example, and conjecture that is the only example.