On bound states of multiple t-quarks due to Higgs exchange
  Froggatt, Nielsen et al suggested that the Higgs boson exchange between top quarks produces enough attraction to generate their multiple bound states. Furthermore they claimed that the system of 6 top and 6 anti-top quarks is bound so strongly that the binding energy nearly compensates the masses of t-quarks, making it very light. We calculated the energy of such states more accurately, variationally and by self-consistent mean field approximation, and found that these state are weakly bound for massless Higgs boson and unbound with the account for its mass. 
Michael Kuchiev, Victor Flambaum, and Edward Shuryak