Interpreting the Higgs

TL;DR

The paper develops an effective-field-theory framework to interpret Higgs data near $m_h=125$ GeV, expressing collider observables in terms of a small set of couplings $c_i$. It provides explicit formulas linking decay and production rates to these couplings and constructs a likelihood to fit them using LHC and Tevatron results across key channels. The fits favor a mildly enhanced coupling to vector bosons, $c_V>1$, and a suppressed effective gluon coupling, $c_g<1$, with a nontrivial best-fit region for other couplings, while the Standard Model point remains disfavored at a modest confidence level given the data available. The work also offers a practical mapping from any future Higgs-rate measurement to constraints on the effective theory, aiding experimental collaborations in reporting and interpreting results.

Abstract

The LHC and Tevatron Higgs data are interpreted as constraints on an effective theory of a Higgs boson with mass close to 125 GeV. We focus on the diphoton, ZZ*, WW* channels at the LHC, and the b-bbar channel at the Tevatron, which are currently the most sensitive probes of a Higgs with such a mass. Combining the available data in these channels, we derive the preferred regions of the parameter space of the effective theory. We further provide the mapping between the effective theory and the relevant Higgs event rates, facilitating future extraction of the preferred region by the ATLAS and CMS collaborations.

Figures (1)

• Figure 1: The allowed parameter space of the effective theory given in Eq. \ref{['eq:1']} derived from the ATLAS, CMS and Tevatron constraints for $m_h = 125$ GeV. We display the $1\sigma$ regions allowed by the LHC inclusive $h \to \gamma\gamma$ channel (mauve), the LHC inclusive $h \to ZZ^{*} \to 4l$ channel (indigo), the CMS dijet class of the $h \to \gamma\gamma$ channel (beige), the ATLAS inclusive $h \to WW^* \to 2l2\nu$ channel (light grey), and the Tevatron $h \to b \bar{b}$ W/Z boson associated channel (peach), The lime green region is the one favored at Ê$90\%$ CL from the combination of these channels. The dashed lines show the SM values.