Single top production via gluon fusion at CERN LHC

Abstract

We calculate the one-loop flavor violating top quark decay $t\ensuremath{\rightarrow}cgg$ in the minimal supersymmetric standard model. We discuss the branching ratios obtained with minimal flavor violation, as well as with soft-supersymmetry induced general flavor violation. Based on this rate we calculate the cross section for the single top quark production via gluon fusion, $gg\ensuremath{\rightarrow}t\overline{c}$, and evaluate its contribution to the cross section for single top quark production in $pp$ collisions at the Large Hadron Collider. We calculate all contributions coming from the standard model and charged Higgs loops, as well as gluino (and neutralino)-up-type squarks, and chargino-down-type squarks loops. Our numerical results show that the gluino and the chargino contributions are largest over the whole parameter range in the unconstrained minimal supersymmetric standard model. While in general the gluino contributions dominate the cross section, this result depends on the supersymmetric flavor violating parameters in the up and down squark sector, the relative mass of the gauginos, and whether or not the grand unified theory relationships between gaugino masses are satisfied. In the most promising scenarios, the $pp\ensuremath{\rightarrow}t\overline{c}+\overline{t}c+X$ cross section at the Large Hadron Collider can reach a few hundred fb.