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→bb-tilde1*g-tilde+b-barb-tilde1g-tilde followed by g-tilde→bb-tilde1*/b-barb-tilde1. The hadronic branching ratio for this channel is (1-3)x10-3, which is of the order of the size of the uncertainty in Rb. 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 Rb; they are even more interesting if the fat bottom jet can be identified