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Particle physics plots
I have seen graphs like this in lots of talks by phenomenologists talking about the Higgs search (see for example FIG 3 in this paper or this blog post or slide 38 of this presentation). I believe the y-axis is some sort of scaling, $R_{lim}$, applied to the expected Standard model signal, but I don't understand what is the source of this in the experiment and why it is different from $1$. It appears to be some sort of a Bayesian calculation but I do not understand what exactly is being calculated.

Thanks!