Tests of the optical theorem

Present experimental data shows that the optical theorem is valid for pi p scattering above 1 GeV/c up to 90% or 95%. The residual discrepancy of 5 or 10% can be explained if some experimental error has not been included in the published values, if the shape assumed for elastic scattering in the analysis is incorrect for values of momentum transfer square near 0.01 (GeV/c)/sup 2/ or less, or if the optical theorem is violated. (16 refs).