An explanation of one loop induced $h\to \mu \tau$ decay

Understand

We discuss a possibility to explain the excess of $h\to\mu\tau$ at one-loop level.

• We introduce three generation of vector-like lepton doublet $L'$ and two singlet scalars $S_{1,2}$ which are odd under $Z_2$, while all the standard model fields are even under this discrete symmetry.
• We show that $S_1$ can be a good dark matter candidate.
• We show that we can explain the dark matter relic abundance, large part of the discrepancy of muon $g-2$ between experiments and the standard model predictions, as well as the $h\to\mu\tau$ excess of $\sim 1$ %, while evading constraints from experiments of dark matter direct detection and charged lepton flavor violating processes.