Abstract
We study the sensitivity to the shape of the Higgs potential of single, double, and triple Higgs production at future e+e− colliders. Physics beyond the Standard Model is parameterised through the inclusion of higher-dimensional operators (Φ†Φ−v2/2)n/Λ(2n−4) with n = 3, 4, which allows a consistent treatment of independent deviations of the cubic and quartic self-couplings beyond the tree level. We calculate the effects induced by a modified potential up to one loop in single and double Higgs production and at the tree level in triple Higgs production, for both Z boson associated and W boson fusion production mechanisms. We consider two different scenarios. First, the dimension six operator provides the dominant contribution (as expected, for instance, in a linear effective-field-theory (EFT)); we find in this case that the corresponding Wilson coefficient can be determined at mathcal{O}left(10%right) accuracy by just combining accurate measurements of single Higgs cross sections at sqrt{widehat{s}}=240-250 GeV and double Higgs production in W boson fusion at higher energies. Second, both operators of dimension six and eight can give effects of similar order, i.e., independent quartic self-coupling deviations are present. Constraints on Wilson coefficients can be best tested by combining measurements from single, double and triple Higgs production. Given that the sensitivity of single Higgs production to the dimension eight operator is presently unknown, we consider double and triple Higgs production and show that combining their information colliders at higher energies will provide first coarse constraints on the corresponding Wilson coefficient.
Highlights
Determining the form of the Higgs potential necessarily implies measuring the strength of the Higgs three- and four- point self-couplings
We study the sensitivity to the shape of the Higgs potential of single, double, and triple Higgs production at future e+e− colliders
Physics beyond the Standard Model is parameterised through the inclusion of higher-dimensional operators (Φ†Φ−v2/2)n/Λ(2n−4) with n = 3, 4, which allows a consistent treatment of independent deviations of the cubic and quartic self-couplings beyond the tree level
Summary
In this work we are interested to the effect induced by the modification V SM(Φ) → V (Φ). For the study of trilinear and quadrilinear Higgs self-couplings at the tree level, only the c6 and c8 Wilson coefficients are relevant. We describe the calculations for single, double and triple Higgs production via WBF, the e+e− → νeνeH(H(H)) processes, or in association with a Z boson, the e+e− → ZH(H(H)) processes We will denote the latter as ZHn. Besides the ZHn and WBF production modes, at e+e− colliders there are other possibly relevant processes such as ttHn, Z-boson-fusion (ZBF) or loop-induced Hn production via photon fusion [50] from the initial-state radiation. [31, 36, 37, 40, 43], in ZHn production we expect a strong dependence of the Higgs self-coupling effects from loop corrections, with larger effects at lower energies. The interference of ZHn-type diagrams with “genuine” WBF configurations is negligible
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