The data collected in 1998 by ALEPH at LEP at a centre-of-mass energy of 18
8.6 GeV, corresponding to an integrated luminosity of 176.2 pb(-1), are ana
lysed to search for invisible decays of a Higgs boson produced in the react
ion e(+) e(-) --> hZ. The number of events found in the data and their prop
erties art: in agreement with the Standard Model expectation. This search r
esults in an improved 95% C.L. lower limit on the Higgs boson mass of 95.4
GeV/c(2), assuming it decays totally invisibly and for a production cross s
ection equal to that of the Standard Model. (C) 1999 Published by Elsevier
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