On theQ-values of the λ0 and the θ0 and on the anomalous V0-decays

A study of 161 V0-decays observed in the momentum chamber of the Ecole Polytechnique at the Pic du Midi has been made. These events correspond to a strict choice based on the measurability of the momenta of both secondairies (better than 10%). The main results are: 1) No direct evidence for anomalous neutral hyperon decays. Upper limits (6 to 8%) can be placed on the existence of various hypothetical modes. 2) TheQ-values for the λ0-decay:\(Q_{\Lambda ^0 } = (37.9 \pm 0.4)\) MeV. 3) The direct identification of the π nature of both secondaries of the θ0-decaymode. 4) TheQ-value for θ0-decay:\(Q_{\theta ^0 } = (217 \pm 4)\) MeV. 5) A direct proof of the non identity of the particles responsible for the θ0-decay and the anomalous V0-decays based on the signincant difference between the number of slow and fast events of each category.