Combination of results from the ATLAS and CMS experiments on anomalous triple gauge couplings in ZZ production from pp collisions at a centre-of-mass energy of 7 TeV at the LHC

A procedure is presented to combine data from the ATLAS and CMS experiments on ZZ production to obtain constraints on anomalous neutral triple gauge boson couplings. Statistical and systematic uncertainties and their correlations are taken into account. Data from pp collisions at a center-of-mass energy of 7 TeV delivered by the LHC are used. The datasets correspond to integrated luminosities of $4.6$ and $5.0~\mathrm{fb}^{-1}$ for ATLAS and CMS, respectively. The combination is performed in the fully leptonic decay channels $\mathrm{ZZ} \to \ell^+ \ell^- \nu \bar{\nu}$ (ATLAS) and $\mathrm{ZZ} \to \ell^+ \ell^- \ell'^+ \ell'^-$ (ATLAS, CMS). Combined limits on the coupling parameters are $-0.010 < f_4^\gamma < 0.011$, $-0.0087 <f_4^Z < 0.0091$, $-0.011 <f_5^\gamma < 0.010$, and $-0.0091 <f_5^Z < 0.0089$ at $95\%$ C.L., where all other parameters are fixed to the standard model values. These results represent the first combined limits of the ATLAS and CMS collaborations for anomalous gauge boson couplings.