Stealth gluons at hadron colliders

We find that a heavy gluon G of mass 800–900 GeV with small, mostly axial-vector couplings to the light quarks and relatively large vector and axial-vector couplings to the top quark can explain the tt¯ forward–backward asymmetry observed at the Tevatron with no conflict with other top-quark or dijet data. The key ingredient is a complete treatment of energy-dependent width effects and a new decay mode G→qQ, where q is a standard quark and Q a vector-like quark of mass 400–600 GeV. We show that this new decay channel makes the heavy gluon invisible in the tt¯ invariant mass distribution and discuss its implications at the Tevatron and the LHC.