Search for an invisibly decaying Higgs boson in e(+)e(-) collisions at 189 GeV

Abstract A searchfor a Higgs bosondecaying into invisibleparticles is performed using the data collected at LEP by the L3 experiment at centre-of-mass energies of 183 GeV and 189 GeV . The integrated luminosities are respectively 55.3 pb −1 and 176.4 pb −1 . The observed candidates are consistent with the expectations from Standard Modelprocesses. In the hypothesis that the production cross section of this Higgs bosonequals the Standard Modelone and the branching ratio into invisibleparticles is 100%, a lower mass limit of 89.2 GeV is set at 95% confidence level.