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

Abstract

A low-energy supersymmetry scenario with a light gluino of mass 12 - 16 GeV and light sbottom (b1) of mass 2 - 6 GeV has been used to explain the apparent overproduction of b quarks at the Tevatron. In this scenario the other mass eigenstate of the sbottom, i.e. b2, 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 LEP via e+ e- -> Z* -> b1 b2* + b1* b2 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 b2. However we find that direct observation of a b2 at the 5-sigma level is possible if it is lighter than 110 - 129 GeV, depending on the sbottom mixing angle |cos(theta_b)| = 0.30 - 0.45. We also show that b2-pair production can be mistaken for production of neutral MSSM Higgs bosons in the channel e+ e- -> h^0 A^0 -> b b-bar b b-bar. Using searches for the latter we place a lower mass limit of 90 GeV on b2.