Large 2HDM(II) one-loop corrections in leptonic tau decays
Institute of Theoretical Physics, University of Warsaw, ul. Hoża 69, 00-681, Warsaw, Poland
2 Laboratoire de Physique Théorique LAPTH, Ch. de Bellevue, B.P 110, 74941, Annecy-le-Vieux, Cedex, France
The one-loop contributions to the branching ratios for leptonic decays are calculated in the CP-conserving 2HDM(II). The analysis is focused on large enhanced contributions. We found that these contributions, involving loops with both neutral and charged Higgs bosons, dominate over the tree-level exchange, the latter one being totally negligible for the decay into e. We derive a simple analytical expression for the one-loop contribution which holds in the large case. We show that the leptonic branching ratios of are complementary to the Higgsstrahlung processes for h(H) and have a large potential in constraining the parameters of the model. In this work we provide upper limits on the Yukawa couplings for both light h and light A scenarios, and we derive a new lower limit on the mass of as a function of which differs significantly from what was considered as a standard constraint based on the tree-level exchange only. Interestingly we also obtain an upper limit on .
© Springer-Verlag, 2005