Measuring the Higgs boson self-coupling at high energy e+e- colliders

Standard model Higgs pair production at e+e- colliders has the capability to determine the Higgs boson self-coupling λ. I present a detailed analysis of the e+e-→ZHH and e+e-→ννHH signal channels, and the relevant background processes, for future e+e- linear colliders with center of mass energies of √(s)=0.5 TeV, 1 TeV, and 3 TeV. Special attention is given to the role nonresonant Feynman diagrams play, and the theoretical uncertainties of signal and background cross sections. I also derive quantitative sensitivity limits for λ. I find that an e+e- collider with √(s)=0.5 TeV can place meaningful bounds on λ only if the Higgs boson mass is relatively close to its current lower limit. At an e+e- collider with √(s)=1 TeV (3 TeV), λ can be determined with a precision of 20%-80% (10%-20%) for integrated luminosities in the few ab-1 range and Higgs boson masses in the range mH=120-180 GeV.