Search for chargino and neutralino production at √s = 181-184 GeV at LEP

Abstract

A search for charginos and neutralinos predicted by supersymmetric theories, has been performed using a data sample of 57 pb-1 at centre-of-mass energies of 181-184 GeV taken with the OPAL detector at LEP. No evidence for chargino or neutralino production has been found. Upper limits on chargino and neutralino pair production (X̃+1 X̃-1 ,X̃01X̃02) cross-sections are obtained as a function of the chargino mass (ℳX̃1±), the lightest neutralino mass (ℳX̃10) and the second lightest neutralino mass (ℳX̃20). For large chargino masses the limits have been improved with respect to the previous analyses at lower centre-of-mass energies. Exclusion regions at 95% confidence level (C.L.) of parameters o..