The (filtered and processed) data

Figure 1 reports the upper plots
Figure: CDF data[9] before and after `arithmetic' background subtraction
of figure 1 of the cited CDF paper. The left side one shows the histogram of the `data',3the jet-jet mass distribution in 8 GeV bins, for a total of about 10800 events4 (points with vertical bars). The colored regions show the predictions split into several contributions, the most important of which is due to the production of two W bosons, or of a W boson together with a Z boson (red). We see that at around 140 GeV there are more events than `expected' (an expression which we shall return to later).

The right side plot shows the data after the contributions called here `background' (all but the red one of the left plot) were subtracted `arithmetically'.5In the five bins between 120 and 160 GeV there are about 230 events (but in the side bins there are even `negative events' whose meaning is only mathematical). That was `the excess'.

Giulio D'Agostini 2012-01-02