Z decay into a bottom quark, a light sbottom, and a light gluino

The discrepancy between the measured and theoretical production cross section of b quarks at the Fermilab Tevatron can probably be explained by the recently proposed scenario of light gluinos of mass 12–16 GeV and light sbottoms of mass 2–5.5 GeV. In this scenario, we study a related process at the Z pole, Z→bb₁^*g̃+b̅ b₁g̃ followed by g̃→bb₁^*/b̅ b₁. The hadronic branching ratio for this channel is (1–3)×10^-3, which is of the order of the size of the uncertainty in R_b. We find that a typical event consists of an energetic prompt bottom jet back to back with a “fat” bottom jet, which consists of a bottom quark and two bottom squarks. Such events with a 10^-3 branching ratio may affect the measurement of R_b; they are even more interesting if the fat bottom jet can be identified.