Weak dipole moments of the tau lepton in models with an extended scalar sector

We consider renormalizable couplings of neutral ϕ, singly ϕ±, and doubly charged ϕ±± scalar bosons to leptons and the Z gauge boson and calculate the one-loop contributions to the anomalous weak magnetic dipole moment (AWMDM) aτW and the weak electric dipole moment (WEDM) dτW of a charged lepton in a model-independent way. The analytic expressions are presented in terms of both parametric integrals and Passarino-Veltman scalar functions. Among the new contributions, there are those arising from the vertices of the type ϕ±W∓Z and Zϕiϕj (i≠j), along with contributions from doubly charged scalar bosons. Both aτW and dτW are evaluated in several scenarios, first in a model-independent way and then within some popular models, such as two-Higgs doublet models (THDMs), multiple-Higgs doublet models and Higgs triplet models. As far as aτW is concerned, its real part reaches values as high as 10−10–10−9 for masses of the new scalar bosons in the 200 GeV range, whereas the imaginary part is 1 or 2 orders of magnitude below. On the other hand, the most promising scenario for a nonvanishing WEDM is offered by a CP-violating THDM in a scenario where the heavy neutral scalar bosons are a mixture of CP eigenstates. It is found that the real part of dτW is of the order of 10−24 ecm and its imaginary part can reach the 10−26 ecm level for masses of the new scalar bosons of the order of a few hundred of GeVs. Both the tau AWMDM and WEDM decrease dramatically as the scalar boson masses increase.