The Faddeev equations for the hypertriton are solved precisely using the Nijmegen hyperonnucleon and realistic NN interactions. The hypertriton turns out to be bound at the experimental value. Thereby the A-:E conversion is crucial. States of the A(:E)NN system with quantum numbers (T, J) different from (0, ~) are not bound. We visualized properties of the hypertriton wave function in various ways.

The π-mesonic decay of the hypertriton is calculated based on a hypertriton wavefunction and 3N scattering states, which are rigorous solutions of 3-body Faddeev equations using realistic NN and hyperon-nucleon interactions. The total π-mesonic decay rate is found to be 92% of the free Λ decay rate, which is close to the experimental data. Together with the nonmesonic decay the total life time of 3 Λ H is predicted to be 2.78 × 10 −10 sec which is 6 % larger than for the free Λ particle. The differential decay rate is evaluated as a function of the pion momentum. The decay into the N + d + π channel is stronger than in the 3N + π channel in contrast to the situation for the nonmesonic decay. The ratio for the decay rate into 3 He + π − to the decay rate into all channels including π − is found to be 0.40, which is close to the experimental value. We visualise the decay into the dominant channel p + d + π − in a Dalitz plot. Finally we compare the polarisation of the outgoing proton in free unpolarised Λ-decay to the polarisation of 3 He in unpolarised 3 Λ H-decay and we compare the closely related asymmetry of π − emitted parallel and antiparallel with respect to the spin-direction for a polarised Λ to the corresponding asymmetry for a polarised 3 Λ H. 21.80.+a, 21.45.+v, 23.40.-s Typeset using REVT E X * present address:

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Quark-model hyperon-nucleon and hyperon-hyperon interactions by the Kyoto-Niigata group are applied to the two-⌳ plus ␣ system in a three-cluster Faddeev formalism using two-cluster resonating-group method kernels. The model fss2 gives a reasonable two-⌳ separation energy ⌬B ⌳⌳ = 1.41 MeV, which is consistent with the recent empirical value, ⌬B ⌳⌳ exp = 1.01± 0.20 MeV, deduced from the Nagara event. Some important effects that are not taken into account in the present calculation are discussed.