Techniques for the measurement of Higgs-boson branching fractions

We describe methods that can be employed at a $\sqrt{s}=500\mathrm{}$ GeV $e^{+}{e}^{-}$ linear collider to measure the branching fractions of a Higgs boson. These methods select one Higgs-boson decay mode above all others with high purity, leaving measurable standard model backgrounds as the only source of contamination. Integrated luminosities of 50 ${\mathrm{fb}}^{-1\mathrm{}}$ are required to obtain statistical errors of 10-20% on the branching fractions to $b\overline{b}$, ${\tau }^{+}{\tau }^{-}$, and $W{W}^{\mathrm{}(*)\mathrm{}}$. For an intermediate-mass Higgs boson this is sufficient to distinguish the minimal supersymmetric standard model Higgs boson from the standard model Higgs boson over most of the supersymmetric parameter space.