We extend the study of Higgs boson couplings in the “golden” $gg\to H\to Z{Z}^{*}\to 4\ell$ channel in two important respects. First, we demonstrate the importance of off-shell Higgs boson production ($gg\to H^{*}\to ZZ\to 4\ell$) in determining which operators contribute to the $HZZ$ vertex. Second, we include the five operators of lowest nontrivial dimension, including the $Z_{\mu }{Z}^{\mu }\square H$ and $H{Z}_{\mu }\square Z^{\mu }$ operators that are often neglected. We point out that the former operator can be severely constrained by the measurement of the off-shell $H^{*}\to ZZ$ rate and/or unitarity considerations. We provide analytic expressions for the off-peak cross sections in the presence of these five operators. On shell, the $Z_{\mu }{Z}^{\mu }\square H$ operator is indistinguishable from its Standard Model counterpart $H{Z}_{\mu }{Z}^{\mu }$, while the $H{Z}_{\mu }\square Z^{\mu }$ operator can be probed, in particular, by the $Z^{*}$ invariant mass distribution.

• Received 28 March 2014

DOI:https://doi.org/10.1103/PhysRevD.91.035011