The effects of Higgs boson couplings through HZZ production at future lepton colliders

Abstract

We focus on the sensitivity of the Higgs-gauge boson couplings at $HγZ$ and $HZZ$ vertices through the process $\ell^- \ell^+ \rightarrow HZZ$ at CLIC and Muon Collider. Signal and relevant backgrounds events are generated in MadGraph within Standard Model Effective Field Theory (SMEFT) framework. These events are passed through Pythia for parton showering, and realistic detector effects are simulated by Delphes. The limits at 95% C.L. on the coefficients $\overline{c}_{HB}$ and $\overline{c}_{HW}$ are obtained at three b-tagging working points; loose, medium, and tight containing the Delphes card from CLIC and Muon Collider, corresponding to b-tagging efficiencies of 90%, 70%, and 50%, respectively. We report that our best 95% C.L. limits on $\overline{c}_{HB}$ and $\overline{c}_{HW}$ coefficients are $[-0.00098; 0.00047]$ and $[-0.00158; 0.00008]$, respectively, at 3 TeV CLIC with an integrated luminosity of 5 ab$^{-1}$, and $[-0.00021; 0.00019]$ and $[-0.00019; 0.00007]$, respectively, at 10 TeV Muon Collider with an integrated luminosity of 10 ab$^{-1}$. These limits are compared with the present experimental and various phenomenological limits.

Figures (11)

• Figure 1: The total cross-section of the process $\ell- \ell+ \rightarrow HZZ$ as a function of coefficients $\overline{c}_\gamma$, $\widetilde{c}_\gamma$, $\overline{c}_{HB}$, $\widetilde{c}_{HB}$, $\overline{c}_{HW}$ and $\widetilde{c}_{HW}$ at the CLIC (left) and the Muon Collider (right).
• Figure 2: The distributions of transverse momentum of the leading b-tagged jet (a), the sub-leading b-tagged jet (b), the leading charged lepton (c), and the sub-leading charged lepton (d) for signal and relevant background processes at CLIC.
• Figure 3: The distributions of the missing energy transverse (a), the transverse momentum balance ratio (b), the scalar sum of the transverse energy (c), and the transverse momentum of two b-tagged jets (d) for signal and relevant background processes at CLIC.
• Figure 4: The distributions of the angular distance between the two b-tagged jets (a), between the two charged leptons (b), and between the leading charged lepton and the leading b-tagged jet (c) for signal and relevant background processes at CLIC.
• Figure 5: The invariant mass distributions of two b-tagged jets (left) and charged lepton pair (right) for signal and relevant background processes at CLIC.