Constraining General Two Higgs Doublet Models by the Evolution of Yukawa   Couplings
  We study how general two Higgs doublet models can be constrained by considering their properties under renormalization group evolution of the Yukawa couplings. We take into account both the appearance of a Landau pole as well as off-diagonal Yukawa couplings leading to flavour changing neutral currents in violation with experimental constraints at the electroweak scale. We find that the latter condition can be used to limit the amount of Z2 symmetry breaking allowed in a given model. 
Johan Bijnens, Jie Lu and Johan Rathsman
hep-ph