Pi-mesonic decay of the hypertriton

Abstract

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.