Study of the Tensor Structure of the Higgs Boson Coupling to Gluons in the $pp \rightarrow H \rightarrow ZZ^{*} \rightarrow 4\ell$ Process with the ATLAS Experiment

The tensor structure of the effective coupling between the Higgs boson and gluons was studied in the $pp \rightarrow H \rightarrow ZZ^{*} \rightarrow 4\ell$ process with dedicated Monte Carlo simulations. In the gluon--gluon fusion production mode of the Higgs boson, angular correlations of final state jets in the process $gg \rightarrow H+2j$ have been used to probe small $\mathcal{CP}$-odd admixtures to the Higgs--gluon coupling. The sensitivity to the sign of the anomalous coupling parameter was studied using simulated proton--proton collisions data in the ATLAS detector at the LHC for integrated luminosities of $36.1$ and $120~\mathrm{fb}^{-1}$ at a centre-of-mass energy of $13~\mathrm{TeV}$ and for integrated luminosities of $300$ and $3000~\mathrm{fb}^{-1}$ at a centre-of-mass energy of $14~\mathrm{TeV}$. As opposed to the production rate information, the shape of the differential distribution of the angular distance between the two final state jets allows for the exclusion of the wrong-sign hypothesis in the currently allowed parameter range with almost $1\sigma$ significance, with more than $1\sigma$ and with more than $4\sigma$ for integrated luminosities of $120$, $300$ and $3000~\mathrm{fb}^{-1}$, respectively.