Residues of Intertwining Operators for U(3,3) and Base Change

Let F be a p-adic local field with characteristic 0 and E/F a quadratic extension. Let sigma = pi(G) circle times pi(H) be a supercuspidal representation of GL(2)(E) x U-E/F (1, 1) with pi(G) conjugate self-dual. In this paper, we use a local approach developed by Shahidi to study the residue of the standard intertwining operator on the parabolic induced representation from sigma to the quasi-split unitary group U-E/F (3, 3) at s = 0, and show that if pi(G) is a standard base change from U-E/F (1, 1), then the residue at s = 0 is nonzero if and only if pi(G) is the standard base change of pi(H).