W ± + 4jet irreducible background events from QCD in top and Higgs searches at the Next Linear Collider

Irreducible background effects due to e ⁺ e ^? → W ^± + bbjj and e ⁺ e ^? → W ^± + jjjj events produced via QCD in top-antitop production and heavy Higgs searches in the bremsstrahlung channel are studied at the Next Linear Collider. Various distributions relevant to phenomenological analyses are given and compared to those expected from top and Higgs signals in the decay channel bb?W ⁺ W ^? → bb?W ^± jj. This analysis follows similar ones previously carried out for the case of the irreducible background proceeding via electroweak interactions