Figure 1

Invariant mass distribution of $\mu^+ \mu^-$ pairs for p--Pb collisions at \eightnn in (a) the p-going and (b) Pb-going data samples, and (c) Pb--Pb collisions at \fivenn. The distributions are obtained from muons with $-4 20$ GeV/$c$ (black points) and compared with POWHEG simulations (red curves), which are normalized to the number of Z bosons in the data. The single like-sign dimuon entry is also shown (orange point) for Pb--Pb collisions, while no entries were found in the p--Pb samples.