Search for the minimum standard model neutral Higgs boson at the L3 experiment at LEP.

Abstract

From a total of 408,000 hadronic events, measured by the L3 detector during both the 1990 and 1991 running periods at LEP, a search for the Minimum Standard Model Higgs has been made in the channel $Z\sp{0}$ $\to$ Higgs + $Z\sp\*$ with $Z\sp\*$ $\to$ $\nu\bar\nu$. Cuts for selecting the Higgs events are decided based on the studies of about 700,000 Monte Carlo events samples. The uncertainty in the selection efficiency has been intensively studied. Detection efficiency for a 50 GeV Higgs reaches 59% with no event surviving from the entire real and simulated data sample. From these data, the lower limit for the Minimum Standard Model Higgs is found to be 50.0 GeV at the 95% confidence level. Together with all the other Higgs search channels at the L3 detector, a lower mass limit of the Minimum Standard Model Higgs has been found to be 52 GeV at 95% confidence level.