CP violation in $h\to \tau\tau$ and LFV $h\to \mu\tau$

TL;DR

This paper discusses how potential lepton flavor violation in Higgs decays, suggested by CMS, could also lead to observable CP violation in tau pair decays, with estimates indicating a possible large asymmetry.

Contribution

It provides a model-independent estimate of CP violation in Higgs decays related to LFV signals, highlighting potential large asymmetries.

Findings

Large CP asymmetry (~25%) is possible in $h o au au$ decays due to LFV signals.

Current experimental constraints do not exclude significant CP violation effects.

LFV in Higgs decays could be linked to measurable CP violation in tau channels.

Abstract

The CMS collaboration has reported a possible lepton flavour violating (LFV) signal $h\to\mu\tau$. Whereas this does not happen in the standard model (SM), we point out that new physics responsible for this type of decay would, in general, also produce charge-parity (CP) violation in $h\to \tau\tau$. We estimate the size of this effect in a model independent manner and find that a large asymmetry, of order 25\%, is allowed by current constraints.