A new analysis improving the evidence of a narrow peak in the invariant-mass distribution of the <img src="/fulltext-image.asp?format=htmlnonpaginated&src=P6858464H73PM80Q_html\10050_2008_5155_Article_IEq1.gif" border="0" alt="$ Λ$" />p system observed in the <img src="/fulltext-image.asp?format=htmlnonpaginated&src=P6858464H73PM80Q_html\10050_2008_5155_Article_IEq2.gif" border="0" alt="$ \barp$" /> annihilation at rest on ⁴He

The presence of a narrow peak in the p invariant-mass distribution observed in the annihilation reaction at rest is discussed again through an analysis procedure which improves the ratio signal/background in comparison with the previous analysis. The peak is centred at 2223.2±3.2 stat ±1.2 syst MeV and has a statistical significance of 4.7 , values compatible with those published previously. If interpreted as the result of the decay into p of a bound system, the corresponding binding energy should be B = - 151.0±3.2 stat ±1.2 syst MeV and the width < 33.9±6.2 MeV. The production rate has a lower limit of 1.2 10 -4 . Data on the annihilation reaction at rest 4 He p p p s X , analyzed for the first time, lead to a result in qualitative agreement with the previous one.