Finite-width effects in the near-threshold ZZZ and ZWW production at ILC

Summary, in English

We calculate the cross-section of the near-threshold off-shell ZZZ and ZW⁺W^- production at the International Linear Collider taking into account their instability and the principal part of next-to-leading order corrections. The calculations are performed in the framework of the model of unstable particles with smeared mass-shell. We show that the contribution of the finite Z/W and H widths (their instability) is large in the Higgs resonance range (about -24% and -18% for ZZZ and ZW⁺W^-, respectively, at √s = 300 GeV) and should be taken into account in the Higgs boson studies at the future International Linear Collider.