Color-singlet and color-octetJ/ψproduction in top quark rare decays

Abstract

$J/\ensuremath{\psi}$ production in top quark rare decays is investigated under the framework of the nonrelativistic QCD factorization formalism. Various production channels are studied, and we find that the contributions from the color-singlet quark fragmentation and the color-octet gluon fragmentation are both over $3$ orders larger than that from the leading order color-singlet process. The numerical results show that the branching ratio $B(\stackrel{\ensuremath{\rightarrow}}{t}c+J/\ensuremath{\psi}+X)$ is about ${10}^{\ensuremath{-}14}$ in the standard model, and ${10}^{\ensuremath{-}10}$ in the minimal supersymmetric standard model.