Potential precision of a direct measurement of the Higgs boson total width at a muon collider

In the light of the discovery of a 126 GeV Standard-Model-like Higgs boson at the LHC, we evaluate the achievable accuracies for direct measurements of the width, mass, and the s-channel resonant production cross section of the Higgs boson at a proposed muon collider. We find that with a beam energy resolution of R=0.01% (0.003%) and integrated luminosity of 0.5 fb^-1 (1 fb ^-1), a muon collider would enable us to determine the Standard-Model-like Higgs width to ±0.35 MeV (±0.15 MeV) by combining two complementary channels of the WW^* and bb̄ final states. A non-Standard-Model Higgs with a broader width is also studied. The unparalleled accuracy potentially attainable at a muon collider would test the Higgs interactions to a high precision.