The Brezis-Nirenberg type critical problem for the nonlinear Choquard equation

We establish some existence results for the Brezis-Nirenberg type problem of the nonlinear Choquard equation -. u = ( O | u (y)| 2 | x - y | d y) | u | 2 2 u + u in O; where Omega is a bounded domain of R (N) with Lipschitz boundary, lambda is a real parameter, N 3, is the critical exponent in the sense of the Hardy-Littlewood-Sobolev inequality.