A correlated background in invariant mass spectra of three-body systems

An analytical approach with Yukawa type three-body wave functions is used t o describe breakup reactions of three-body systems in the sudden approximat ion. The model is applied to the two-neutron halo nuclei Li-11, He-6 and co rrelations in the relative energy distributions of the break-up fragments a re found. Since no final state interactions are included in the model the d erived energy distributions should be present in experimental invariant mas s spectra as a background, on which possible resonances will be superposed. Interesting low energy features are found for the total excitation energy of Li-11 and also for the relative energy distributions in the binary subsy stems of Li-11 and He-6. (C) 2000 Elsevier Science B.V. All rights reserved .