Yukawa sector for LFV in $h\to \mu\tau$ and CP violation in $h\to \tau\tau$

TL;DR

This paper investigates models that could explain the potential lepton flavor violation in Higgs decays and explores associated CP violation effects, analyzing the implications of different Yukawa textures and existing experimental constraints.

Contribution

It introduces specific models that generate large $h\to\mu\tau$ rates and examines their predictions for CP violation in $h\to\tau\tau$, considering different Yukawa matrix textures.

Findings

Large $h\to\mu\tau$ rates can be achieved in certain models.

Predictions for CP violation depend on Yukawa matrix textures.

Constraints from current experiments limit the parameter space.

Abstract

The Higgs boson discovered at the LHC opened a new chapter for particle physics. Its properties need to be studied in detail to distinguish a purely standard model (SM) Higgs boson from one of many scalars in an enlarged Higgs sector. The CMS collaboration has reported a possible lepton flavor violating (LFV) signal $h\to\mu\tau$, which if confirmed, implies that the Higgs sector is larger than in the SM. New physics responsible for this type of decay may, in general, also introduce other observable effects such as charge-parity (CP) violation in $h\to \tau\tau$. We study two types of models that single out the third generation and can induce large $h \to \mu\tau$ rates with different consequences for CP violation in $h \to \tau \tau$. Predictions for the size of the CP violating couplings require knowledge of the lepton Yukawa matrices and we discuss this in the context of two different textures considering all existing constraints.