English

Charged lepton flavor violation in light of Muon $g-2$

High Energy Physics - Phenomenology 2022-02-15 v3

Abstract

The recent confirmation of the muon g2g-2 anomaly by the Fermilab g-2 experiment may harbinger a new era in μ\mu and τ\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 HH and AA, that have flavor changing neutral couplings ρτμ\rho_{\tau\mu} and ρμτ\rho_{\mu\tau} at 20\sim 20 times the usual tau Yukawa coupling, λτ\lambda_\tau. Taking ρλmin(,)\rho_{\ell\ell^\prime}\sim \lambda_{ \rm min(\ell, \ell^\prime)}, we show that the above solution to muon g2g-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 μeγ\mu \to e \gamma, μeee\mu \to eee and μNeN\mu N \to e N, and τ\tau decays τμγ\tau \to \mu \gamma and τμμμ\tau \to \mu\mu\mu. A similar one-loop diagram with ρeτ=ρτe=O(λe)\rho_{e\tau}= \rho_{\tau e} = {\cal O}(\lambda_e) induces μeγ\mu \to e\gamma, bringing the rate right into the sensitivity of the MEG~II experiment. The μeγ\mu e\gamma dipole can be probed further by μ3e\mu \to 3e and μNeN\mu N \to e N. With its promised sensitivity range and ability to use different nuclei, the μNeN\mu N \to eN conversion experiments can not only make discovery, but access the extra diagonal quark Yukawa couplings ρqq\rho_{qq}. For the τ\tau lepton, we find that τμγ\tau \to \mu\gamma would probe ρττ\rho_{\tau\tau} down to λτ\lambda_\tau or lower, while τ3μ\tau \to 3\mu would probe ρμμ\rho_{\mu\mu} to O(λμ){\cal O}(\lambda_{\mu}).

Keywords

Cite

@article{arxiv.2107.14114,
  title  = {Charged lepton flavor violation in light of Muon $g-2$},
  author = {Wei-Shu Hou and Girish Kumar},
  journal= {arXiv preprint arXiv:2107.14114},
  year   = {2022}
}

Comments

8 pages, 3 figures, v2: matches journal version; v3: includes additional references related to muon g-2 SM prediction