The Gauge-Higgs Legacy of the LHC Run I

TL;DR

This work develops a linear effective field theory with ten dimension-6, CP- and flavor-selected operators to probe deviations in the Higgs and electroweak gauge sectors at the LHC. It first performs a global fit to Run I di-boson data to constrain triple gauge vertices, obtaining bounds on the Wilson coefficients $f_B$, $f_W$, and $f_{WWW}$ that are stronger than LEP limits. It then combines these di-boson constraints with Higgs data to tightly constrain the full set of Higgs–gauge operators, notably reducing correlations and removing secondary solutions, highlighting the gauge–Higgs interplay. The results demonstrate that di-boson information is essential for robust EFT analyses of the Higgs sector and establishes a framework for exploiting Run I data to its full potential while cautioning about EFT validity at high momenta.

Abstract

The effective Lagrangian expansion provides a framework to study effects of new physics at the electroweak scale. To make full use of LHC data in constraining higher-dimensional operators we need to include both the Higgs and the electroweak gauge sector in our study. We first present an analysis of the relevant di-boson production LHC results to update constraints on triple gauge boson couplings. Our bounds are several times stronger than those obtained from LEP data. Next, we show how in combination with Higgs measurements the triple gauge vertices lead to a significant improvement in the entire set of operators, including operators describing Higgs couplings.

Figures (6)

• Figure 1: Results of the TGV analysis from LHC Run I. We show all two-dimensional profile likelihoods in the three-dimensional parameter space at 95% CL (2dof) for the individual channels as well as their combination.
• Figure 2: Results of the TGV analysis in terms of two-dimensional profile likelihoods from LHC Run I and from LEP LEP2002. We also show the statistical combination of both.
• Figure 3: Correlated profile likelihood for sets of two Wilson coefficients. In the first row we include only LHC Run I Higgs data, including kinematic distributions, as shown in Fig. 11 of Ref. legacy. In the second row we add the Run I di-boson results probing anomalous TGV interactions (as well as the corresponding LEP results). The black points indicate $-2\log L=5.99$. The corresponding one-dimensional profile likelihoods can be found in Fig. \ref{['fig:errorbars']}.
• Figure 4: Allowed 95% CL ranges for individual Wilson coefficients $f_x/\Lambda^2$ from a one-dimensional profile likelihood. We show results from Run I Higgs observables only (red bars) and for a combined Higgs plus TGV analysis (blue). For the upper panels we allow for sign changes in the individual Yukawa couplings, while in the lower panel we fix their signs to the Standard Model one.
• Figure 5: Leading $p_{T,\ell}$ distribution for the 8 TeV ATLAS $WW$ analysis atlas8ww. The red histogram shows the ATLAS background estimate (excluding the SM $WW$ prediction), while the green histogram shows the total SM prediction once $WW$ processes are added. The observed events are shown as dots, with error bars accounting for the statistical uncertainty. The dashed lines indicate the effects of dimension--six Wilson coefficients.