Search for chargino and neutralino production
GeV at LEP
The OPAL Collaboration
G.Abbiendi - et al.
2 Dipartimento di Fisica dell' Università di Bologna and INFN,
40126 Bologna, Italy
Received: 14 October 1999 / Published online: 6 March 2000 - © Springer-Verlag 2000
A search for charginos and neutralinos, predicted by supersymmetric theories, is performed using a data sample of 182.1 pb-1taken at a centre-of-mass energy of 189 GeV with the OPAL detector at LEP. No evidence for chargino or neutralino production is found. Upper limits on chargino and neutralino pair production ( , ) cross-sections are obtained as a function of the chargino mass ( ), the lightest neutralino mass ( ) and the second lightest neutralino mass ( ). Within the Constrained Minimal Supersymmetric Standard Model framework, and for GeV, the 95% confidence level lower limits on are 93.6 GeV for and 94.1 GeV for . These limits are obtained assuming a universal scalar mass 500 GeV. The corresponding limits for all m0 are 78.0 and 71.7 GeV. The 95% confidence level lower limits on the lightest neutralino mass, valid for any value of are 32.8 GeV for GeV and 31.6 GeV for all m0.
Copyright Società Italiana di Fisica, Springer-Verlag 2000