The Standard Model of particle physics is a successfully tested theory to describe interactions of elementary particles. However, experimental data hints us at possible new physics beyond Standard Model should exist. After the discovery of the Higgs boson, measurements of its property and couplings to other particles are essential to search for new physics.
Multi-Higgs production processes are important to reconstruct the Higgs potential and to study the mechanism of electroweak symmetry breaking. Possible new physics deviation can be observed in these processes. We study the multi-Higgs production via gluon-gluon fusion and vector-boson fusion at hadron collider using an effective Lagrangian to describe potential new physics.
For the multi-Higgs production process via gluon-gluon fusion, we explore the potential for the discovery of the triple-Higgs signal in the 2b2l±4j + /E decay channel at a 100 TeV hadron collider. Our detector analysis shows that the discovery of Standard Model signals via this channel is a challenging task for the future hadron collider. Combined with the projected constraints from single and double Higgs-boson production, the measurement of triple Higgs process can further reduces the allowed parameter space.
For the multi-Higgs production process via vector-boson fusion, our numerical calculation shows the energy dependence of the effective parameters. Experimentally, a measurement of triple-Higgs final state via vector-boson fusion process is very challenging due to its small cross section, even on future high energy colliders, but the constraints on anomalous couplings should be obtained. Our numerical results describe the potential for constraining these couplings at the LHC and at future hadron colliders. We also derive theoretical constraints on the parameter space from the unitarity of 2->n scattering amplitudes and apply the results to VV->hh and hhh processes.