A $L_\mu - L_\tau$ theory of Higgs flavor violation and $(g-2)_\mu$

Understand

Several experiments reported hints for the violation of lepton flavor or lepton flavor universality in processes involving muons.

• Most prominently, there is the hint for a non-zero rate of the flavor violating Higgs decay $h \to \tau\mu$ at the LHC, as well as the hint for lepton flavor universality violation in rare $B$ meson decays at LHCb.
• In addition, also the long standing discrepancy in the anomalous magnetic moment of the muon motivates new physics connected to muons.
• A symmetry which violates lepton flavor universality, is $L_\mu-L_\tau$: the difference of muon-number and tau-number.