Fourth generation bound states

Abstract

We investigate the spectrum and wave functions of q̅ ′q′ bound states for heavy fourth generation quarks (q′) that have a very small mixing with the three observed generations of standard model quarks. Such bound states come with different color, spin and flavor quantum numbers. Since the fourth generation Yukawa coupling, λ_q′, is large we include all perturbative corrections to the potential between the heavy quark and antiquark of order λ_(q′)^(2)N_c/16π^2 where N_c is the number of colors, as well as relativistic corrections suppressed by (v/c)^2. We find that the lightest fourth generation quark masses for which a bound state exists for color octet states. For the color singlet states, which always have a bound state, we analyze the influence that the Higgs couplings have on the size and binding energy of the bound states.