experimental physics

The European Physical Journal C - Particles and Fields

, Volume 32, Issue 3, pp 303-322

First online:

Study of Z pair production and anomalous couplingsin e + e- collisions at \(\sqrt{s}\) between 190 GeV and 209 GeV

  • The OPAL Collaboration

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A study of Z-boson pair production in e + e- annihilation at center-of-mass energies between 190 GeV and 209 GeV is reported. Final states containing only leptons, (\(\ell^{ + }\ell^{-}\ell^{ + }\ell^{-}\) and \(\ell^{ + }\ell^{-}\nu\overline{\nu}\)), quark and lepton pairs, (\(\mathrm{q \bar{q}}\ell^{ + }\ell^{-}\), \(\mathrm{q \bar{q}}\nu\overline{\nu}\)) and only hadrons (\(\mathrm{q \bar{q}}\mathrm{q \bar{q}}\)) are considered. In all states with at least one Z boson decaying hadronically, lifetime, lepton and event-shape tags are used to separate \(\mathrm{b \bar{b}}\) pairs from \(\mathrm{q \bar{q}}\) final states. Limits on anomalous ZZ\(\gamma\) and ZZZ couplings are derived from the measured cross sections and from event kinematics using an optimal observable method. Limits on low scale gravity with large extra dimensions are derived from the cross sections and their dependence on polar angle.