Extracting the Intermediate-Mass Higgs Resonance at Photon-Photon Colliders

Abstract

We address the problem of how to extract the signal of a Higgs within the intermediate mass range at a photon-photon collider that has a wide energy spectrum. All backgrounds from two-jets production are included: direct, so-called resolved and twice-resolved as well as single $Z$ and $W$ production. Uncertainties in the evaluation of the QCD-initiated processes such as the choice of structure function and the issue of radiative corrections are discussed. We consider various combinations of the polarizations and invariant mass resolutions as well as jet-tagging strategies with different efficiencies. The analysis is based on an automatized technique that, given a specific detector and machine configuration, returns the optimal set of cuts corresponding to the best significance one may hope to achieve for each particular Higgs mass. We find that at a photon machine obtained from a 500GeV \epm\ linear collider with $\int\!{\cal L}=10$~fb$^{-1}$ it will be possible to extract a Higgs signal in the range 110--140~GeV, while with the same luminosity, a 350~GeV option not only extends the discovery limit down to 90~GeV but gives much better significance levels.