The residual spectrum of U(n,n); contribution from Borel subgroups

In this paper we study the residual spectrum of the quasi-split unitary group G=U(n,n) defined over a number field F, coming from the Borel subgroups, L2dis(G(F)∖G(A))T. Due to lack of information on the local results, that is, the image of the local intertwining operators of the principal series, our results are incomplete. However, we describe a conjecture on the residual spectrum and prove a certain special case by using the Knapp-Stein R-group of the unitary group.