A new analysis improving the evidence of a narrow peak in the invariant-mass distribution of the Lambdap system observed in the bar{{p}} annihilation at rest on 4He

The presence of a narrow peak in the $ Lambda$ p invariant-mass distribution observed in the $ bar{{p}}$ annihilation reaction at rest $ensuremath bar{p} {}^4mathrm{He}rightarrow ppi^-ppi^+pi^-n X$ 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 $ sigma$ , values compatible with those published previously. If interpreted as the result of the decay into $ Lambda$ p of a $ensuremath { }_{bar{K}}{}^2mathrm{H}$ bound system, the corresponding binding energy should be B = - 151.0±3.2_stat±1.2_syst MeV and the width $ Gamma_{{FWHM}}^{}$ < 33.9±6.2 MeV. The production rate has a lower limit of 1.2 10^-4. Data on the $ bar{{p}}$ annihilation reaction at rest $ bar{{p}}$ ⁴He $ rightarrow$ p $ pi^{-}_{}$ p $ pi^{-}_{}$ p _s X , analyzed for the first time, lead to a result in qualitative agreement with the previous one.