Neutralino mass bounds at the upgraded LEP collider

Assuming that no supersymmetric signature will be found at the upgraded LEP collider we derive lower bounds on the masses of the four neutralinos χ10 in the Minimal Supersymmetric Standard Model (MSSM). We consider the recently published results from the search for the light chargino χ1± and the next-to-lightest neutralino χ20 at LEP1.5 and study the consequences of possible future lower χ1± and χ20 mass limits between 65 and 95 GeV. For a chargino mass bound of 66.8 GeV at LEP1.5, a massless neutralino is not excluded for tan β < 1.2. If either tan β > 2.3 or the gluino mass mg > 160 GeV, we find mχ10 > 28 GeV. A possible chargino bound mχ1± > 95 GeV at LEP2 would raise this bound to 31 GeV (for all tan β) or 44 GeV (tan β > 2).