Physics opportunities at mu+ mu- Higgs factories

We update theoretical studies of the physics opportunities presented by {mu}{sup +} {mu}{sup -} Higgs factories. Interesting measurements of the Standard Model Higgs decays into {bar b}b, {tau}{sup +} {tau}{sup -} and WW* may be possible if the Higgs mass is less than about 160 GeV, as preferred by the precision electroweak data, the mass range being extended by varying appropriately the beam energy resolution. A suitable value of the beam energy resolution would also enable the uncertainty in the b-quark mass to be minimized, facilitating measurements of parameters in the MSSM at such a first {mu}{sup +} {mu}{sup -} Higgs factory. These measurements would be sensitive to radiative corrections to the Higgs-fermion-antifermion decay vertices, which may violate CP. Radiative corrections in the MSSM may also induce CP violation in Higgs-mass mixing, which can be probed via various asymmetries measurable using polarized {mu}{sup +} {mu}{sup -} beams. In addition, Higgs-chargino couplings may be probed at a second {mu}{sup +} {mu}{sup -} Higgs factory.