"Figure 2 Left" of "Measurement and effective field theory interpretation of the photon-fusion production cross section of a pair of W bosons in proton-proton collisions at $\sqrt{s}$ = 13 TeV"

Observed and predicted $p_{T}^{e\mu}$ distributions for events with $N_{tracks}=0$, using 2016--2018 data. The distributions are shown after the maximum likelihood fit to the data ('postfit distributions'). The observed data and their associated Poissonian statistical uncertainty are shown with black markers with vertical error bars. The uncertainty band accouts for all sources of background and signal uncertainty, systematic as well as statistical, after the fit. The last bin includes the overflow. The lower panels show the ratio of data to sum of signal and background contributions, before (prefit, open red circles) and after (black full markers) the maximum likelihood fit.