Estimate the branching ratios for the four-lepton decays (10.58) and (10.60) of the Higgs boson by relating them to the branching ratios for other reactions listed in Table 10.1. Use your answers to estimate the average total number of Higgs decays (10.58) for an LHC energy of 7€“8 TeV, where the Higgs production cross-section is about 20 pb with an error of approximately 15% and an integrated luminosity of 25 pb^ˆ’1. Compare your results with the number actually observed as shown in Figure 10.29.

Figure 10.29

Table 10.1 Predicted decay widths T and branching ratios B for the main decay modes of the Higgs boson and for the rare but important decay Y. The errors arise from uncertainties in the input parameters. (eV) Decay mode B (57.5 + 1.8) x 10-2 (21.6 0.9) 10-2 (8.6 + 0.8) x 10-2 (6.3 +0.3) 10-2 (2.9 + 0.3) 10-2 (2.7 +0.1) x 10-2 (2.3+0.1) 10-3 bb 2.35 + 0.11 w+f' 0.88 +0.01 0.35 +0.02 gg + 0.26 0.01 0.12 +0.01 (11.00.1) 103 (9.5 0.1) 103 Zff 25 Data Background Higgs signal 20 15 10 100 120 140 160 180 M(GeV/c*) 41 Events/(3GEV/c) 80