Higgs couplings: disentangling New Physics with off-shell measurements

TL;DR

This Letter shows that a much more model-independent interpretation of the Higgs boson couplings is possible using off-shell measurements based on the high-invariant mass cross section of the process gg→ZZ.

Abstract

After the discovery of a scalar resonance, resembling the Higgs boson, its couplings have been extensively studied via the measurement of various production and decay channels on the invariant mass peak. Recently, it has been suggested the possibility to use off-shell measurements: in particular, CMS has published results based on the high- invariant mass cross section of the process $gg \to ZZ$, which contains the contribution of the Higgs. While this measurement has been interpreted as a constraint on the Higgs width after very specific assumptions are taken on the Higgs couplings, in this letter we show that a much more model-independent interpretation is possible.

Figures (1)

• Figure 1: Left: Dependence on the new-physics mass of the cross section of the $gg \to VV$ process in the off-shell region, normalized to the SM cross section for the same process. Right: Regions allowed at 1 and 2 $\sigma$ by the on-peak coupling constraints (diagonal bands), compared to the off-shell iso-cross section lines for the $gg \to VV$ process at 1.2, 1.50 and 2 times the SM cross section. The dot and black line correspond to the $\kappa_{gg}=0$ case where the CMS bound can be recast to the constraint $\kappa_t<2.3$.