Measurements of the Higgs boson production, fiducial and differential cross-sections in the four lepton decay channel using 164 fb${}^{-1}$ of data collected at $\sqrt{s}$ = 13.6 TeV with the ATLAS detector

Inclusive, differential and production-mode cross-section measurements of the Higgs boson are performed in the $H\to Z{Z}^{\ast }\to 4\mathrm{\ell }$ decay channel. The analysis uses proton-proton collision data produced at the Large Hadron Collider at a centre-of-mass energy of $\sqrt{s}=13.6$ TeV and recorded with the ATLAS detector, corresponding to an integrated luminosity of 164 fb${}^{-1}$. The inclusive fiducial cross-section for the $H\to Z{Z}^{\ast }\to 4\mathrm{\ell }$ process is measured to be ${\sigma }_{\text{fid}}=3.65_{-0.33}^{+0.35}\text{ fb}$, in agreement with the Standard Model prediction of ${\sigma }_{\text{fid}}^{\text{SM}}=3.68\pm 0.17\text{ fb}$. Differential cross-sections are measured as a function of key kinematic observables of the Higgs boson and the four-lepton final state. Cross-sections are measured for the main production-modes in several exclusive regions of the Higgs boson production phase space and combined to measure an overall Higgs boson signal strength, defined as the measured cross-section normalised to the SM prediction, of $\mu =0.99\pm 0.13$. The results are interpreted in terms of modifications of Higgs boson couplings using the $\kappa$ framework, within the Standard Model Effective Field Theory, and in scenarios probing the Higgs boson self-coupling. All the results are consistent with Standard Model expectations.