Multiple Higgs and vector boson production beyond the Standard Model

A primary goal of present and future colliders is measuring the Higgs couplings to Standard Model (SM) particles. Any observed deviation from the SM predictions for these couplings is a sign of new physics whose energy scale can be bounded from above by requiring tree-level unitarity. In this paper, we extend previous work on unitarity bounds from the Higgs cubic coupling to Higgs couplings to vector bosons and top quarks. We find that HL-LHC measurements of these couplings compatible with current experimental bounds may point to a scale that can be explored at the HL-LHC or a next-generation collider. Our approach is completely model-independent: we assume only that there are no light degrees of freedom below the scale of new physics, and allow arbitrary values for the infinitely many couplings beyond the SM as long as they are in agreement with current measurements. We also extend and clarify the methodology of this analysis, and show that if the scale of new physics is above the TeV scale, then the deviations can be described by the leading higher-dimension gauge invariant operator, as in the SM effective field theory.

“…• Previous work has focused on unitarity constraints on 2 → 2 partial wave amplitudes [8-11, 15, 16] and inclusive cross sections [12,13,[17][18][19]. We follow ref.…”

Section: Jhep07(2021)056mentioning

confidence: 99%

Higgs coupling measurements and the scale of new physics

Abu-Ajamieh

Chang

Miranda

et al. 2021

“…This category includes also 2 → 2 scattering processes involving transverse gauge bosons, where, because of the helicity structure of the amplitudes, the dimension-6 operators do not interfere with the SM while the dimension-8 ones do [79]. Another example is the triple Higgs production by vector boson fusion whose energy-growing piece originates from D ≥ 8 operators only [80,81].…”

Section: • Zero At Leading Ordermentioning

confidence: 99%

On the validity of the effective field theory approach to SM precision tests

Contino

Falkowski

Goertz

et al. 2016

181

196

We discuss the conditions for an effective field theory (EFT) to give an adequate low-energy description of an underlying physics beyond the Standard Model (SM). Starting from the EFT where the SM is extended by dimension-6 operators, experimental data can be used without further assumptions to measure (or set limits on) the EFT parameters. The interpretation of these results requires instead a set of broad assumptions (e.g. power counting rules) on the UV dynamics. This allows one to establish, in a bottom-up approach, the validity range of the EFT description, and to assess the error associated with the truncation of the EFT series. We give a practical prescription on how experimental results could be reported, so that they admit a maximally broad range of theoretical interpretations. Namely, the experimental constraints on dimension-6 operators should be reported as functions of the kinematic variables that set the relevant energy scale of the studied process. This is especially important for hadron collider experiments where collisions probe a wide range of energy scales.

“…[130], while a study at the LHC has been recently carried out in ref. [131] and triple Higgs production by gluon fusion has also been studied in ref. [132]).…”

Section: What Can Be Learned From Triple Higgs Production?mentioning

confidence: 99%

Strong Higgs interactions at a linear collider

Contino

Grojean

Pappadopulo

et al. 2014

Abstract:We study the impact of Higgs precision measurements at a high-energy and high-luminosity linear electron positron collider, such as CLIC or the ILC, on the parameter space of a strongly interacting Higgs boson. Some combination of anomalous couplings are already tightly constrained by current fits to electroweak observables. However, even small deviations in the cross sections of single and double Higgs production, or the mere detection of a triple Higgs final state, can help establish whether it is a composite state and whether or not it emerges as a pseudo-Nambu-Goldstone boson from an underlying broken symmetry. We obtain an estimate of the ILC and CLIC sensitivities on the anomalous Higgs couplings from a study of W W scattering and hh production which can be translated into a sensitivity on the compositeness scale 4πf , or equivalently on the degree of compositeness ξ = v 2 /f 2 . We summarize the current experimental constraints, from electroweak data and direct resonance searches, and the expected reach of the LHC and CLIC on ξ and on the scale of the new resonances.