The real part of the elastic scattering amplitude at nonzero transferred   momenta
  The model-independent solution of the s-channel unitarity condition for the imaginary part of the hadronic elastic scattering amplitude outside the diffraction peak allows to make conclusions about its real part at nonzero transferred momenta. The asymptotical properties of the ratio of the real to imaginary part of the amplitude are discussed. In particular, it is explicitly shown that the ratio changes its sign at a defnite value of the transferred momentum. Some comments concerning the present day experimental results about the behavior of the differential cross-section of elastic scattering outside the diffraction cone are given. 
I. M. Dremin
hep-ph