  We analyse the tension between the (indirect) measurements of the total cross
section, and show the impact of various assumptions on the extraction of the
parameters from the elastic scattering amplitude, with a special attention to
the total cross section. In particular, the determination of the phase of the
elastic scattering amplitude will play an important role, and we shall study it
via dispersion relations. We shall also examine the origin of the dependence on
momentum transfer of the slopes of the different parts of the scattering
amplitude in different models. We shall also give the results of another
similar analysis based on a Regge-trajectory approach for the hadron scattering
amplitude.
