Figure 1

Invariant-mass distribution of unlike-sign muon pairs with $\pt>20$ GeV$c$ in the Pb-going (left panel) and p-going (right panel) data samples. In the p-going one, the solid line represents the distribution obtained using POWHEG simulations and normalised to the number of Z candidates in the data.
[png]   [pdf]   [eps]
[png]   [pdf]   [eps]