Higgs boson production at the Compton collider

The high precision determination of the partial width $\Gamma \left(\overrightarrow{H}\gamma \gamma \right)$ of an intermediate mass Higgs boson is among the most important measurements at a future photon-photon collider. Recently it was shown that large non-Sudakov as well as Sudakov double logarithmic corrections can be summed to all orders in the background process $\gamma \overrightarrow{\gamma }q\overline{q},$ $q=\{b,c\},$ from an initially polarized $J_z=0\mathrm{}$ state. In addition, running coupling corrections were included exactly to all orders by employing the renormalization group. Thus all necessary theoretical results for calculating the Higgs signal and the non-Higgs continuum background contributions to the process $\gamma \overrightarrow{\gamma }q\overline{q}$ are now known. We are therefore able to present for the first time precise predictions for the measurement of the partial width $\Gamma \left(\overrightarrow{H}\gamma \gamma \right)$ at the Compton collider $\left(\gamma \gamma \right)$ option at a future linear $e^{+}{e}^{-}$ collider. The interplay between signal and background is very sensitive to the experimental cuts and the ability of the detectors to identify b quarks in the final state. We investigate this in some detail using a Monte Carlo analysis, and conclude that a measurement with a 2% statistical accuracy should be achievable. This could have important consequences for the discovery of physics beyond the standard model, in particular for large masses of a pseudoscalar Higgs boson as the decoupling limit is difficult and for a wide range of $\tan \beta$ impossible to cover at the CERN LHC proton-proton collider.