Heavy Charged Leptons from Type-III Seesaw and Pair Production of the Higgs Boson H at the International Linear e⁺e^- Collider

Type-III seesaw scenario predicts the existence of the heavy charged leptons, which might generate observable signals in future collider experiments. We consider the contributions of these new particles to the process e⁺e^- →HH. We find that, for the large mixing between the light and heavy leptons, these new particles can indeed generate significant contributions to this process.