A lepton collider in the multi-TeV range has the potential to measure the trilinear Higgs self-coupling constant $lambda_{hhh}$ via the W-fusion mode $ell^+ell^- rightarrow u_ell bar{ u}_ell h h$. In this paper we do a generator-level study to explo
re how center-of-mass energy spread, cone size, tracking resolution, and collision energy range affect how precisely a muon collider can measure $lambda_{hhh}$ in comparison to an $e^+e^-$ collider. The smaller spread in center-of-mass energy and higher energy range of a muon collider improve cross section while the larger cone required to reduce beam-induced background hinders detection of double-Higgs events. Our results motivate a more detailed study of a multi-TeV muon collider and innovative detector and analysis technologies required for background rejection and precision measurement.
In light of the recent discovery of an approximately 126 GeV Higgs boson at the LHC, the particle physics community is beginning to explore the possibilities for a next-generation Higgs factory particle accelerator. In this report we study the s-chan
nel resonant Higgs boson production and Standard Model backgrounds at a proposed mu+mu- collider Higgs factory operating at center-of-mass energy sqrt(s) = M_H with a beam width of 4.2 MeV. We study PYTHIA-generated Standard Model Higgs and background events at the generator level to identify and evaluate important channels for discovery and measurement of the Higgs mass, width, and branching ratios. We find that the H^0 -> bb and H^0 -> WW^* channels are the most useful for locating the Higgs peak. With an integrated luminosity of 1 fb^-1 we can measure a 126 GeV Standard Model Higgs mass accurately to within 0.25 MeV and its total width to within 0.45 MeV. Our results demonstrate the value of the high Higgs cross section and narrow beam resolution potentially achievable at a muon collider.
