6 The Discovery of the Higgs Boson at the LHC
299
Fig. 6.20 (a) Distribution of events as a function of the decimal logarithm of S/B. The shaded
histogram shows the expected background distribution. The two hatched histograms, each stacked
on top of the background histogram, show the signal expectation for the SM (μ ttH = 1) and the
observed (μ ttH = 1.26) signal strengths. The lower panel shows the ratios of the expected signal
and observed results relative to the expected background. (b) Best fit value of the ttH signal strength
modifier μ ttH , with its 1σ and 2σ confidence intervals for upper section) the five individual decay
channels considered, middle section) the combined result for 7 + 8 TeV alone and for 13 TeV
alone, and lower section) the overall combined result. The SM expectation is shown as a dashed
vertical line
the background-only hypothesis for m H = 125.09. The combined best-fit signal
strength normalized to the standard model prediction is 1.26 +0.31 –0.26 . Figure 6.20a
shows the distribution of events as a function of the decimal logarithm of S/B, where
S and B are the expected postfit signal (with μ ttH = 1) and background yields,
respectively, in each bin of the distributions considered in this combination. The
shaded histogram shows the expected background distribution. The two hatched
histograms, each stacked on top of the background histogram, show the signal
expectation for the SM (μ ttH = 1) and the observed (μ ttH = 1.26) signal strengths.
The lower panel shows the ratios of the expected signal and observed results relative
to the expected background. Figure 6.20b plots the ttH signal strength modifiers,
μ ttH , for the various selections and the overall combined result. The SM expectation
is shown as a dashed vertical line.
299
Fig. 6.20 (a) Distribution of events as a function of the decimal logarithm of S/B. The shaded
histogram shows the expected background distribution. The two hatched histograms, each stacked
on top of the background histogram, show the signal expectation for the SM (μ ttH = 1) and the
observed (μ ttH = 1.26) signal strengths. The lower panel shows the ratios of the expected signal
and observed results relative to the expected background. (b) Best fit value of the ttH signal strength
modifier μ ttH , with its 1σ and 2σ confidence intervals for upper section) the five individual decay
channels considered, middle section) the combined result for 7 + 8 TeV alone and for 13 TeV
alone, and lower section) the overall combined result. The SM expectation is shown as a dashed
vertical line
the background-only hypothesis for m H = 125.09. The combined best-fit signal
strength normalized to the standard model prediction is 1.26 +0.31 –0.26 . Figure 6.20a
shows the distribution of events as a function of the decimal logarithm of S/B, where
S and B are the expected postfit signal (with μ ttH = 1) and background yields,
respectively, in each bin of the distributions considered in this combination. The
shaded histogram shows the expected background distribution. The two hatched
histograms, each stacked on top of the background histogram, show the signal
expectation for the SM (μ ttH = 1) and the observed (μ ttH = 1.26) signal strengths.
The lower panel shows the ratios of the expected signal and observed results relative
to the expected background. Figure 6.20b plots the ttH signal strength modifiers,
μ ttH , for the various selections and the overall combined result. The SM expectation
is shown as a dashed vertical line.