  The pi-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 pi-mesonic decay rate is found to be 92% of the free Lambda decay rate,
which is close to the experimental data. Together with the nonmesonic decay the
total life time of 3Lambda H is predicted to be 2.78 x 10^-10 sec which is 6 %
larger than for the free Lambda particle. The differential decay rate is
evaluated as a function of the pion momentum. The decay into the N+d+pi channel
is stronger than in the 3N+pi channel in contrast to the situation for the
nonmesonic decay. The ratio for the decay rate into 3He + pi^- to the decay
rate into all channels including pi^- is found to be 0.40, which is close to
the experimental value. We visualise the decay into the dominant channel
p+d+pi^- in a Dalitz plot. Finally we compare the polarisation of the outgoing
proton in free unpolarised Lambda-decay to the polarisation of 3He in
unpolarised 3_Lambda H-decay and we compare the closely related asymmetry of
pi^- emitted parallel and antiparallel with respect to the spin-direction for a
polarised Lambda to the corresponding asymmetry for a polarised 3_Lambda H.

Nuclear Theory