Figure 3

Invariant mass distribution for $\Lambda \mathrm{p} \pi^{-} $ for the Pb--Pb data corresponding to $ 19.3 \times 10^{6}$ central events. The left arrow indicates the sum of the masses of the constituents ($\Lambda\Lambda$) of the possible bound state. A signal for the bound state is expected in the region below this sum. For the speculated resonant state a signal is expected between the $\Lambda\Lambda$ and the $\Xi$p (indicated by the right arrow) thresholds. The dashed line is an exponential fit to estimate the background.