On the production of a composite Higgs boson

TL;DR

This work presents a model‑independent framework to compute gluon‑fusion Higgs production in theories where the Higgs is a pseudo‑Nambu–Goldstone boson. By using an effective Lagrangian with three operators—O_H, O_y, and O_g—the authors show how the production rate depends primarily on the decay constant f and is only weakly sensitive to heavy top partners’ masses. They provide a general prescription to compute the corresponding coefficients c_H, c_y, and c_g, and apply it to several explicit composite Higgs models, including various little‑Higgs variants and minimal composite Higgs models. Across models, electroweak constraints push f to values that yield a significant suppression of the gluon‑fusion rate relative to the SM, typically in the 10–30% range, highlighting a robust phenomenological signature of compositeness at the LHC. The results also stress the need for precise measurements of Higgs production rates to probe or constrain these scenarios.

Abstract

We present a prescription for computing the gluon fusion production rate of a composite Higgs boson, which arises as a pseudo-Nambu-Goldstone boson, using effective lagrangians. The calculation incorporates three different effects due to the composite nature of the Higgs, some of which were neglected previously. We apply the prescription to models with and without the collective breaking mechanism. In sharp contrast with the case of a fundamental Higgs scalar, the rate only depends on the decay constant "f" and is not sensitive to masses of new particles. After including electroweak constraints, there is a substantial reduction in the rate, in the range of 10 -- 30 % or greater.

Figures (6)

• Figure 1: Diagrams $(a)$ and $(d)$ are the contributions to ${\cal O}_g$ from the SM top and a heavy fermions $T$ or scalar $\tilde{t}$ . Diagrams $(b)$ and $(c)$ summarize the effects of ${\cal O}_H$ and ${\cal O}_y$.
• Figure 3: The ratio of the Higgs production rates in the gluon fusion channel in the littlest Higgs model over the SM expectation. The three curves, from top to bottom, are for $c_-/c_+= 1$, $0.3$, and $0$, respectively. Precision electroweak constraints require $f \agt$$1.2$ TeV.
• Figure 4: The ratio of the Higgs production rates in the gluon fusion channel in the (new) littlest Higgs model with T-parity Pappadopulo:2010jx over the SM expectation. Precision electroweak constraints is quite weak and allow $f \agt 500$ GeV.
• Figure 5: The ratio of the Higgs production rates in the gluon fusion channel in the littlest Higgs model with the custodial symmetry over the SM expectation. The three curves, from top to bottom, are for $\lambda_{\mathbf{1}}^- /\lambda_{\mathbf{1}}^+ =\lambda_{\mathbf{3}}^- /\lambda_{\mathbf{3}}^+= 1$, $0.3$, and $0$, respectively. Precision electroweak constraints require $f \agt$$700$ GeV.
• Figure 6: The ratio of the Higgs production rates in the gluon fusion channel in the holographic Higgs model over the SM expectation. With some mild tuning, precision electroweak constraints allow $400$ GeV $\alt f \alt 800$ GeV.