Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Limits on Anomalous Couplings of the Higgs to Electroweak Gauge Bosons from LEP and LHC

Eduard Masso, Veronica Sanz

TL;DR

This work adopts an effective-field-theory approach with four dimension-6 operators (O_W, O_B, O_WW, O_BB) to quantify possible new-physics deviations in Higgs couplings to electroweak gauge bosons, under the assumption that the 125 GeV state is a fundamental scalar. By combining LEP precision electroweak data with LHC Higgs measurements, the authors derive constraints on the operator coefficients ε_i, finding that LEP strongly limits ε_W and ε_B, while LHC diphoton data tightly constrain ε_WW and ε_BB, with significant implications for H→γZ and for UV scenarios such as supersymmetry and radion models. They translate operators into modified HVV couplings and study their phenomenology in Higgs decays, including a detailed treatment of H→γγ and H→Zγ channels, as well as angular studies in WW* decays. Prospects for 2012 data suggest further tightening of the ε_WW–ε_BB sector and improved sensitivity to HAZ couplings, offering a robust framework to test new physics at the TeV scale.

Abstract

In this paper we assume the Higgs is an elementary scalar, and study how new physics could affect its couplings to electroweak gauge bosons. Adding LHC data to LEP data provides new, more stringent limits, particularly when the Higgs to two photon decay signal strength is taken into account. We then study the effect of anomalous angular correlations in the decay to WW*. We obtain a new limit on the rare decay to photon-Z, and use it to constrain Supersymmetry, to find that staus with large mixing would be most sensitive to this channel. We also use these limits to constrain radion exchange in Warped Extra-Dimensions, finding a limit on the radion mass and interaction scale of the order of TeV. Finally, we have extrapolated the current data to obtain prospects for the full 2012 dataset.

Limits on Anomalous Couplings of the Higgs to Electroweak Gauge Bosons from LEP and LHC

TL;DR

This work adopts an effective-field-theory approach with four dimension-6 operators (O_W, O_B, O_WW, O_BB) to quantify possible new-physics deviations in Higgs couplings to electroweak gauge bosons, under the assumption that the 125 GeV state is a fundamental scalar. By combining LEP precision electroweak data with LHC Higgs measurements, the authors derive constraints on the operator coefficients ε_i, finding that LEP strongly limits ε_W and ε_B, while LHC diphoton data tightly constrain ε_WW and ε_BB, with significant implications for H→γZ and for UV scenarios such as supersymmetry and radion models. They translate operators into modified HVV couplings and study their phenomenology in Higgs decays, including a detailed treatment of H→γγ and H→Zγ channels, as well as angular studies in WW* decays. Prospects for 2012 data suggest further tightening of the ε_WW–ε_BB sector and improved sensitivity to HAZ couplings, offering a robust framework to test new physics at the TeV scale.

Abstract

In this paper we assume the Higgs is an elementary scalar, and study how new physics could affect its couplings to electroweak gauge bosons. Adding LHC data to LEP data provides new, more stringent limits, particularly when the Higgs to two photon decay signal strength is taken into account. We then study the effect of anomalous angular correlations in the decay to WW*. We obtain a new limit on the rare decay to photon-Z, and use it to constrain Supersymmetry, to find that staus with large mixing would be most sensitive to this channel. We also use these limits to constrain radion exchange in Warped Extra-Dimensions, finding a limit on the radion mass and interaction scale of the order of TeV. Finally, we have extrapolated the current data to obtain prospects for the full 2012 dataset.

Paper Structure

This paper contains 15 sections, 41 equations, 10 figures, 1 table.

Table of Contents

  1. Introduction
  2. The language of effective operators
  3. Constraints from Precision Electroweak Physics
  4. Limits in the one parameter space
  5. Limits on the two parameter space
  6. LHC Bounds
  7. The translation between effective operators and Higgs couplings
  8. The Impact of Higgs data in the effective operator basis
  9. The diphoton channel
  10. The WW and ZZ channels
  11. Combined Constraints on Anomalous Couplings
  12. Limits on the Coupling of the Higgs to Photon-Z
  13. Constraining New Physics: A Toy Example
  14. Prospects for the 2012 run
  15. Conclusions

Figures (10)

  • Figure 1: The 68%, 95% and 99% CL allowed regions in the parameters $(\epsilon_W,\epsilon_B)$ and $(\epsilon_{WW},\epsilon_{BB})$. We use the limits (\ref{['STbounds']} with the U parameter fixed to zero as well as (\ref{['expg1Z']}) and (\ref{['expkg']}).
  • Figure 2: Signal stregths used in this paper. The upper three correspond to CMS data, and the last three numbers are the ATLAS combination results.
  • Figure 3: . The total cross section as a function of the operators $\epsilon_{WW,BB}$ for ATLAS (left) and CMS (right) combined data. Green, yellow and gray areas correspond to 1, 2 and 3 $\sigma$ respectively.
  • Figure 4: The effect of the different Lorentz structures in the dilepton angular distributions. We plot the $\Delta \Phi_{\ell\ell}$ distribution for the three vertices considered here.
  • Figure 5: . The total cross section as a function of the operator $\epsilon_{W}$ for ATLAS (left) and CMS (right) combined data. Green, yellow and gray areas correspond to 1, 2 and 3 $\sigma$ respectively. The blue-dashed line corresponds to having the efficiencies effect into account.
  • ...and 5 more figures