Precision W -Boson and Higgs Boson Mass Determinations at Muon Colliders

Precise determinations of the masses of the W boson and of the top quark could stringently test the radiative structure of the Standard Model (SM) or provide evidence for new physics. We analyze the excellent prospects at a muon collider for measuring MW and mt in the W W and ZH threshold regions. With an integrated luminosity of 10 (100) fb, the W -boson mass could be measured to a precision of 20 (6) MeV, provided that theoretical and experimental systematics are understood. A measurement of ∆MW = 6 MeV would constrain the mass of a ∼ 100 GeV Higgs to about ±10 GeV. We demonstrate that a measurement at future colliders of the Bjorken process. With an integrated luminosity of 100 fb it is possible to measure the Standard Model Higgs mass to within 45 MeV at a μμ collider for mh = 100 GeV.