Prospects for and Implications of Measuring the Higgs to Photon-Photon Branching Ratio at the Next Linear $e^{+}{e}^{-}$ Collider

Abstract

We evaluate the prospects for measuring $BR(h\to {\hat{I}}^3{\hat{I}}^3)$ for a Standard-Model-like Higgs boson at the Next Linear $e^{+}{e}^{-}$ Collider in the $e^{+}{e}^{-}\to Z^{\ast }\to Zh$ and $e^+e^-\toν_e\antiν_e h$ production modes. Relative merits of different machine energy/luminosity strategies and different electromagnetic calorimeter designs are evaluated. We emphasize the importance of measuring $BR(h\to {\hat{I}}^3{\hat{I}}^3)$ in order to obtain the total width of a light Higgs boson and thereby the $b\anti b$ partial width that will be critical in discriminating between the SM Higgs and the Higgs bosons of an extended model.

11 pages, full postscript file also available via anonymous ftp at ftp://ucdhep.ucdavis.edu/gunion/htogamgam.ps. Revisions are substantial; in particular, the $WW$-fusion Higgs production mode is now considered in addition to the $Zh$ Higgs production mode