Integral Representation for U_3 × GL_2

Abstract

Gelbart and Piatetskii-Shapiro constructed various integral representations of Rankin–Selberg type for groups G × GL_n, where G is of split rank n. Here we show that their method can equally well be applied to the product U_3 × GL_2, where U_3 denotes the quasisplit unitary group in three variables. As an application, we describe which cuspidal automorphic representations of U_3 occur in the Siegel induced residual spectrum of the quasisplit U_4.

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