Charged lepton flavor violation in light of muon g-2

Abstract

The recent confirmation of the muon g-2 anomaly by the Fermilab g-2 experiment may harbinger a new era in mu and tau physics. In the context of general two Higgs doublet model, the discrepancy can be explained via one-loop exchange of sub-TeV exotic scalar and pseudoscalars, namely H and A, that have flavor changing neutral couplings rho _{tau mu } and rho _{mu tau } at sim 20 times the usual tau Yukawa coupling, lambda _tau . Taking rho _{ell ell ^prime }sim lambda _{ mathrm min(ell , ell ^prime )}, we show that the above solution to muon g-2 then predicts enhanced rates of various charged lepton flavor violating processes, which should be accessible at upcoming experiments. We cover muon related processes such as mu rightarrow e gamma , mu rightarrow eee and mu N rightarrow e N, and tau decays tau rightarrow mu gamma and tau rightarrow mu mu mu . A similar one-loop diagram with rho _{etau }= rho _{tau e} = mathcal{O}(lambda _e) induces mu rightarrow egamma , bringing the rate right into the sensitivity of the MEG II experiment. The mu egamma dipole can be probed further by mu rightarrow 3e and mu N rightarrow eN. With its promised sensitivity range and ability to use different nuclei, the mu N rightarrow eN conversion experiments can not only make discovery, but access the extra diagonal quark Yukawa couplings rho _{qq}. For the tau lepton, we find that tau rightarrow mu gamma would probe rho _{tau tau } down to lambda _tau or lower, while tau rightarrow 3mu would probe rho _{mu mu } to mathcal{O}(lambda _{mu }).