Charged Scalar Particles and $τ$ Leptonic Decay

Abstract

Charged scalar particles introduced in some extensions of the standard model can induce $τ$ leptonic decay at tree level. We find that with some charged SU(2)-singlet scalar particles, like ones introduced in Zee-type models, $τ$ leptonic decay width is always smaller than what is predicted by the standard model, therefore they may offer a natural solution to $τ$ decay puzzle. To be more specific, we examine some Zee-type models in detail to see if at the same time they are acceptable in particle physics, cosmology and astrophysics. It is shown that $τ$ decay data do put some constrains on these models.