The dips observed in the differential cross sections of elastic $\mathrm{pp}$ and $p\overline{p}$ scattering are studied in terms of the locations of the zeros of the real and imaginary parts of the amplitude and of the sign of real part at large $|t|.$ It is confirmed that the differences in shapes of the dips in the $\mathrm{pp}$ and $p\overline{p}$ systems are determined by a change of sign of the real tail, which seems to be determined by perturbative QCD contributions.

• Received 15 July 1999

DOI:https://doi.org/10.1103/PhysRevD.61.077507