On a Possible Stationary Point in High-Energy Scattering
  We discuss a curious observation: at energies from the ISR and up to the LHC, inclusively, the differential cross-section of elastic proton-proton scattering remains almost energy-independent at the transferred momentum t =-0.21 GeV^2 at the level of 7,5 mb/GeV^2.The latter value can be considered as a prediction for dsigma/dt at 13 TeV. We also obtain a lower bound for the forward pp slope at 13 GeV. 
V.A. Petrov and A.P. Samokhin
hep-ph hep-ex