Single Higgs boson production at electron-positron colliders in gauge-Higgs unification

AbstraktAbstract

We examine contributions to single Higgs boson production processes via Z0 and W0 bosons in the SU(3)×SO(5)×U(1) gauge-Higgs unification (GHU) model. In particular, we analyze the cross sections of three single Higgs boson production processes e^−e^+ → Zh, e^−e^+ → ννh, and e^−e^+ → e^−e^+h in the SM and the GHU model. For the Higgs strahlung process e^−e^+ → Zh, we show that for a parameter region satisfying the current experimental constraints, a maximum deviation from the SM is about up to 6% for the center-of-mass energy of the initial electron and positron \sqrt{s}=250 GeV and that from the SM is about up to 20% for \sqrt{s}=500 GeV, depending on the initial polarization of electron and positron. The deviation from the SM is monotonically increasing with respect to \sqrt{s} for \sqrt{s}≲ 1 TeV. By using the Higgs strahlung process, it is possible to explore up to the region of tens of TeV in terms of the Kaluza-Klein (KK) mass. We also show that the sign of the bulk mass of a lepton multiplet in the GHU model can be determined by examining the deviation of the left-right symmetry of the e−eþ → Zh process from the SM. The contributions to the cross sections of the e^−e^+ → ννh and e^−e^+ → e^-e^+h processes via the Z' and W' bosons are relatively small compared to that for e^−e^+ → Zh at least for \sqrt{s} ≤ 1 TeV. As is the same as in the SM, the e^−e^+ → ννh process gives a main contribution to the single Higgs boson production processes for \sqrt{s} ≳ 500 GeV, but large deviations from the SM are only observed on energy scales close to the masses of the first KK gauge bosons or higher.

We examine contributions to single Higgs boson production processes via Z0 and W0 bosons in the SU(3)×SO(5)×U(1) gauge-Higgs unification (GHU) model. In particular, we analyze the cross sections of three single Higgs boson production processes e^−e^+ → Zh, e^−e^+ → ννh, and e^−e^+ → e^−e^+h in the SM and the GHU model. For the Higgs strahlung process e^−e^+ → Zh, we show that for a parameter region satisfying the current experimental constraints, a maximum deviation from the SM is about up to 6% for the center-of-mass energy of the initial electron and positron \sqrt{s}=250 GeV and that from the SM is about up to 20% for \sqrt{s}=500 GeV, depending on the initial polarization of electron and positron. The deviation from the SM is monotonically increasing with respect to \sqrt{s} for \sqrt{s}≲ 1 TeV. By using the Higgs strahlung process, it is possible to explore up to the region of tens of TeV in terms of the Kaluza-Klein (KK) mass. We also show that the sign of the bulk mass of a lepton multiplet in the GHU model can be determined by examining the deviation of the left-right symmetry of the e−eþ → Zh process from the SM. The contributions to the cross sections of the e^−e^+ → ννh and e^−e^+ → e^-e^+h processes via the Z' and W' bosons are relatively small compared to that for e^−e^+ → Zh at least for \sqrt{s} ≤ 1 TeV. As is the same as in the SM, the e^−e^+ → ννh process gives a main contribution to the single Higgs boson production processes for \sqrt{s} ≳ 500 GeV, but large deviations from the SM are only observed on energy scales close to the masses of the first KK gauge bosons or higher.