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

Abstract

The discrepancy between the measured and theoretical production cross section of $b$ quarks at the 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, $Z\to b{\tilde{b}}_1^{\ast }\tilde{g}+\bar{b}{\tilde{b}}_1\tilde{g}$ followed by $\tilde{g}\to b{\tilde{b}}_1^{\ast }/\bar{b}{\tilde{b}}_1$. The hadronic branching ratio for this channel is $(1-3)\times 10^{-3}$, which is of 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 $R_b$; even more interesting if the ``fat'' bottom jet can be identified.

Comments: 14 pages, references are added