Invariant-mass distribution of $\rm e\Xi$ pairs for $\Xi_{\rm c}^{0} \rightarrow \Xi^- {\rm e}^+ \rm \nu_{\rm e}$ in $4 <   p_{\rm T} <   6$ GeV/$c$, in the high- (left) and low- (right) multiplicity classes. The blue filled distribution shows the total fit and the coloured lines indicate the different sources contributing to the fit.