Can there be a heavy sbottom hidden in three-jet data at CERN LEP?

Abstract

A low-energy supersymmetry scenario with a light gluino of mass 12--16 GeV and light sbottom $({b}_{1})$ of mass 2--6 GeV has been used to explain the apparent overproduction of b quarks at the fermilab Tevatron. In this scenario the other mass eigenstate of the sbottom, i.e., ${b}_{2},$ is favored to be lighter than 180 GeV due to constraints from electroweak precision data. We survey its decay modes in this scenario and show that decay into a b quark and gluino should be dominant. Associated sbottom production at CERN LEP via ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{Z}^{*}\ensuremath{\rightarrow}{b}_{1}{b}_{2}^{*}+{b}_{1}^{*}{b}_{2}$ is studied and we show that it is naturally a three-jet process with a small cross section, increasingly obscured by a large standard model background for heavier ${b}_{2}.$ However we find that direct observation of a ${b}_{2}$ at the $5\ensuremath{\sigma}$ level is possible if it is lighter than 110--129 GeV, depending on the sbottom mixing angle $|\mathrm{cos}{\ensuremath{\theta}}_{b}|=0.30--0.45.$ We also show that ${b}_{2}$-pair production can be mistaken for production of neutral minimal supersymmetric standard model Higgs bosons in the channel ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{h}^{0}{A}^{0}\ensuremath{\rightarrow}b\overline{b}b\overline{b}.$ Using searches for the latter we place a lower mass limit of 90 GeV on ${b}_{2}.$