Real part of the K±p forward scattering amplitude at 4.2, 7 and 10 GeV/c

The differential cross section of K−p and K+p elastic scattering has been measured at 4.2, 7 and 10 GeV/c in the very forward region of scattering angles. The measurements have been made at the CERN PS by means of multiwire proportional chambers and counters. The region of momentum transfers t is 0.001 ⩽ |t| ⩽ 0.10 GeV2 at the highest momentum and 0.001 ⩽ |t| ⩽ 0.03 GeV2 at the lowest. Over these regions the Coulomb and the nuclear amplitudes reach their maximum interference. We have used a parametrisation of the above amplitudes to determine the value of the real part of the nuclear forward scattering amplitude. A dispersion relation fit has then been performed using these and earlier measurements; the asymptotic behaviour of the K±p real parts has been examined in the light of this fit.