Double Higgs-boson bremsstrahlung fromWandZbosons at supercolliders

We calculate the production of two standard-model neutral Higgs bosons via bremsstrahlung from a single W or Z boson in pp or $e^{+}$ $e^{\mathrm{-}}$ collisions at supercollider energies. Observation of these processes would test the predicted HHH, HVV, and HHVV couplings (V=W or Z). For $e^{+}$ $e^{\mathrm{-}}$→ZHH we extend previous cross-section calculations to a more comprehensive range of energies and Higgs-boson masses, that may be accessible to future machines; we also give final-particle distributions. In the pp case we present the first calculations of the processes pp→HHVX; the cross sections are comparable to other double Higgs-boson production processes for a range of energies and masses. The presence of W or Z accompanying the Higgs-boson pair has distinct practical advantages for triggering and for separating the final state from backgrounds.