Search for supersymmetric partners of top and bottom quarks at sqrt(s) = 189 GeV

TL;DR

This paper reports on searches for supersymmetric top and bottom quark partners using LEP data at 189 GeV, finding no deviations from the Standard Model and setting exclusion limits on their masses.

Contribution

It provides new exclusion limits on squark and neutralino masses by analyzing LEP data at 189 GeV and combining with previous results.

Findings

No evidence of supersymmetric partners was observed.

Excluded regions in the squark-neutralino mass plane at 95% confidence level.

Enhanced constraints compared to previous LEP data analyses.

Abstract

Searches for supersymmetric partners of top and bottom quarks are presented using data taken by the DELPHI experiment at LEP in 1997 and 1998. No deviations from standard model expectations are observed in these data sets, which are taken at centre-of-mass energies of 183 GeV and 189 GeV and correspond to integrated luminosities of 54 pb^{-1} and 158 pb^{-1}. These results are used in combination with those obtained by DELPHI at lower centre-of-mass energies to exclude regions in the squark-neutralino mass plane at 95% confidence level.