Invariant-mass distributions for events in the 0n0n (left) and XnXn (right) neutron classes measured at mid (top) and forward rapidity (bottom). The solid black markers represent data, the vertical line through each of them is the associated statistical uncertainty. The blue lines depict the fit models, described in the text, which are composed of a signal (shown in magenta) and a background (shown in green) contribution. In the lower left plot the contribution from $\Psip$ is clearly visible (shown in yellow).