Browder spectra of closed upper triangular operator matrices

Let T-B = [A B 0 D] be an unbounded upper operator matrix with diagonal domain, acting in H circle plus K, where H and K are Hilbert spaces. In this paper, some su fficient and necessary conditions are characterized under which T-B is Browder (resp., invertible) for some closable operator B with D(B) superset of D( D). Further, a su fficient and necessary condition is given under which the Browder spectrum (resp., spectrum) of T-B coincides with the union of the Browder spectrum (resp., spectrum) of its diagonal entries.