Distorted-wave impulse-approximation evaluation of sum rule for hypernuclear formation in forward (K−,π−)

The summed hypernuclear formation cross section at O° in ($K^{-},{\pi }^{-}$) reactions, for kaons of laboratory momentum $p_K=900\mathrm{}$ MeV/c, is evaluated within the distorted-wave impulse approximation using a non-energy-weighted sum rule obtained with the closure assumption. A detailed study of distortion effects results in agreement with eikonal estimates. Possible corrections to closure are mentioned. The final results are in strong disagreement with cross sections recently measured by Brückner et al.