We present a study of $\mu \mu \mu \mu$, $eeee$, and $\mu \mu ee$ events using $1{\mathrm{fb}}^{-1}$ of data collected with the D0 detector at the Fermilab Tevatron $p\overline{p}$ Collider at $\sqrt{s}=1.96\mathrm{TeV}$. Requiring the lepton pair masses to be greater than 30 GeV, we observe one event, consistent with the expected background of $0.13\pm 0.03$ events and with the predicted standard model $ZZ$ and $Z{\gamma }^{*}$ production of $1.71\pm 0.15$ events. We set an upper limit on the $ZZ$ and $Z{\gamma }^{*}$ cross section of 4.4 pb at the 95% C.L. We also derive limits on anomalous neutral trilinear $ZZZ$ and $ZZ{\gamma }^{*}$ gauge couplings. The one-parameter 95% C.L. coupling limits with a form-factor scale $\Lambda =1.2\mathrm{TeV}$ are $-0.28<f_{40}^Z<0.28$, $-0.31<f_{50}^Z<0.29$, $-0.26<f_{40}^{\gamma }<0.26$, and $-0.30<f_{50}^{\gamma }<0.28$.

• Received 5 December 2007

DOI:https://doi.org/10.1103/PhysRevLett.100.131801