{ "id": "math/0605251", "version": "v1", "published": "2006-05-10T08:12:41.000Z", "updated": "2006-05-10T08:12:41.000Z", "title": "Brown Measures of Unbounded Operators Affiliated with a Finite von Neumann Algebra", "authors": [ "Uffe Haagerup", "Hanne Schultz" ], "comment": "50 pages", "categories": [ "math.OA" ], "abstract": "In this paper we generalize Brown's spectral distribution measure to a large class of unbounded operators affiliated with a finite von Neumann algebra. Moreover, we compute the Brown measure of all unbounded R-diagonal operators in this class. As a particular case, we determine the Brown measure of z=xy^{-1}, where (x,y) is a circular system in the sense of Voiculescu, and we prove that for all positive integers n, z^n is in L^p(M) iff 0