New expressions for the wave operators of Schroedinger operators in R^3
  We prove new and explicit formulas for the wave operators of Schroedinger operators in R^3. These formulas put into light the very special role played by the generator of dilations and validate the topological approach of Levinson's theorem introduced in a previous publication. Our results hold for general (not spherically symmetric) potentials decaying fast enough at infinity, without any assumption on the absence of eigenvalue or resonance at 0-energy. 
S. Richard, R. Tiedra de Aldecoa
math-ph math.FA math.MP math.SP