Search for the Standard Model Higgs Boson at LEP

TL;DR

This paper reports the combined analysis of LEP collider data, setting a lower limit of 114.1 GeV on the Standard Model Higgs boson mass and indicating a slight preference for a mass around 115.6 GeV.

Contribution

It presents the first combined search for the Standard Model Higgs boson using data from all four LEP experiments, improving sensitivity and setting new mass bounds.

Findings

Lower bound of 114.1 GeV at 95% confidence level

Preference for a Higgs mass of 115.6 GeV

3.4% probability background explains observed effect

Abstract

The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have collected 2465 pb-1 of e+e- collision data at energies between 189 and 209 GeV, of which 542 pb-1 were collected above 206 GeV. Searches for the Standard Model Higgs boson have been performed by each of the LEP collaborations. Their data have been combined and examined for their consistency with the Standard Model background and various Standard Model Higgs boson mass hypotheses. A lower bound of 114.1 GeV has been obtained at the 95% confidence level for the mass of the Higgs boson. The likelihood analysis shows a preference for a Higgs boson with a mass of 115.6 GeV. At this mass, the probability for the background to generate the observed effect is 3.4%.