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High Energy Physics - Phenomenology, hep-ph
Abstract:
We review how the muon anomalous magnetic moment ($g-2$) and the quest for
lepton flavor violation are intimately correlated. Indeed the decay $\mu \to e
\gamma$ is induced by the same amplitude for different choices of in- and
outgoing leptons. In this work, we try to address some intriguing questions
such as: Which hierarchy in the charged lepton sector one should have in order
to reconcile possible signals coming simultaneously from $g-2$ and LFV? What
can we learn if the $g-2$ anomaly is confirmed by the upcoming flagship
experiments at FERMILAB and J-PARC, and no signal is seen in the decay $\mu
\rightarrow e\gamma$ in the foreseeable future? On the other hand, if the $\mu
\rightarrow e\gamma$ decay is seen in the upcoming years, do we need to
necessarily observe a signal also in $g-2$? In this attempt, we generally study
the correlation between the two phenomena in a detailed analysis of simplified
models. We derive master integrals and fully analytical and exact expressions
for both phenomena. We investigate under which conditions the observations can
be made compatible and discuss their implications. Lastly, we discuss in this
context several extensions of the SM, such as the Minimal Supersymmetric
Standard Model, Left-Right symmetric model, $B-L$ model, scotogenic model, two
Higgs doublet model, Zee-Babu model, 3-3-1 model, and $L_{\mu}-L_{\tau}$
models.
