Energy Dependence of Helicity--Flip Amplitudes in the Small--Angle   Elastic pp--Scattering
  We discuss a role of the double helicity-flip amplitudes and derive new unitary bounds for these amplitudes in elastic $pp$-scattering at small values of $t$. We show that the usual assumption on the smallness of such amplidudes can be justified only in the shrinking with energy region of small $t$ values. 
S. M. Troshin, N. E. Tyurin