%0 Journal Article
%T Estimates of holomorphic functions in zero-free domains
%A Alexander Borichev
%A Vesselin Petkov
%J Mathematics
%D 2009
%I arXiv
%X We study functions f(z) holomorphic in the upper half plane and having no zeros when the imaginary part of z is between 0 and 1, and we obtain a lower bound for the modulus of f(z) in this strip. In our analysis we deal with scalar functions f(z) as well as with operator valued holomorphic functions I+A(z) assuming that A(z) is a trace class operator in the upper half plane and I+A(z) is invertible in the same strip and is unitary on the real line.
%U http://arxiv.org/abs/0906.1827v1