On accelerants and their analogs, and on the characterization of the   rectangular Weyl functions for Dirac systems with locally square-integrable   potentials on a semi-axis
  We characterize the set of rectangular Weyl matrix functions corresponding to Dirac systems with locally square-integrable potentials on a semi-axis and demonstrate a new way to recover the locally square-integrable potential from the Weyl function. Important interconnections between our approach and accelerants of convolution operators are discussed as well. 
Alexander Sakhnovich
math.SP math.CA math.FA