Top quark decay into charged Higgs boson in a general Two-Higgs-Doublet Model: implications for the tevatron data

We analyze the unconventional top quark decay mode t --> H(+)b at the quant um level within the context of general Two-Higgs-Doublet Models by includin g the full electroweak effects from the Yukawa couplings. The results are p resented in the on-shell renormalization scheme with a physically well moti vated definition of tan beta. While the QCD corrections have been taken int o account in the current experimental analyses of that decay, the electrowe ak effects have always been neglected. However, we find that they can be ra ther large and could dramatically alter the interpretation of the present d ata from the Tevatron collider. For instance, in large portions of the para meter space the electroweak effects prevent the Tevatron data from placing any bound at all to the charged Higgs mass for essentially any value of tan beta. (C) 1998 Elsevier Science B.V. All rights reserved.