This thesis is a presentation of an analysis of the $ZZ\to 4\ell$ ($\ell =e,\mu$) process in proton-proton collisions with centre-of-mass energy $s$ = 13 TeV at the LHC during 2015 and 2016 (a total integrated luminosity of 36.1 fb$\mathrm{<mrow\; data-mjx-texclass="ORD">-1</mrow>}$), using the ATLAS detector.

Candidate $ZZ\to 4\ell$ events are selected in the three decay channels, $4e$, $2e2\mu$ and $4\mu$. The cross section of the $ZZ\to 4\ell$ process is measured in four fiducial regions closely matching the detector acceptance: one for each decay channel ($4e$, $2e2\mu$ and $4\mu$) and one for the combination of all decay channels. The total cross section of $pp\to ZZ$ is measured in a phase-space in which both $Z$ bosons have a mass $mZ$ in the range 66 GeV $ < m_{Z} < $ 116 GeV to be 16.5 $\pm 0.5$ (stat.) $\pm 0.4$ (syst.) $\pm 0.5$ (lumi.)$$ pb which is consistent with a next-to-next-to-leading-order prediction of $16.9-0.5+0.6$ pb.

Observed event yields in four bins of transverse momentum are used to set 95{%} CL$\mathrm{<mrow\; data-mjx-texclass="ORD">s</mrow>}$ limits on four neutral triple gauge couplings ($fiV$, $V=Z,\gamma$, $i=4,5$) which parameterise an effective $ZZV$ vertex (assuming both $Z$ bosons are on shell). The obtained limits are of the order of .