As described in section 2.6.1 a better decay mode will be the rare decay H with a branching ratio around 10- 3. The theory describing the decay can be found in section 2.3.3 and the dominant production mechanism through gluon fusion in section 2.2.1.
The H decay has to be observed above a large background of irreducible photon-photon background. The invariant mass distribution of the photon-photon background will vary smoothly across the mass range from 80-130 GeV. A Higgs particle has thus to be discovered as a slight bump on top of a well calibrated background.
In this chapter the main focus will be on the mass resolution of the H signal and / separation. The mass resolution is determined solely by the quality of the detector as the natural Higgs width below the threshold of the H W +W - decay is of the order 1 MeV, which is much narrower than any obtainable mass resolution. Good mass resolution is important to concentrate as much as possible of the signal into a narrow peak, which will be easier to observe above the continuum background.