Constraining Low-Scale Flavor Models with $\boldsymbol{(g-2)_μ}$ and Lepton Flavor Violation

Abstract

We present here two concrete examples of models where a sub-TeV scale breaking of their respective T 13 and A 5 flavor symmetries is able to account for the recently observed discrepancy in the muon anomalous magnetic moment, (g−2) µ . Similarities in the flavor structures of the charged-lepton Yukawa matrix and dipole matrix yielding (g − 2) µ give rise to strong constraints on low-scale flavor models when bounds from lepton flavor violation (LFV) are imposed. These constraints place stringent limits on the off-diagonal Yukawa structure, suggesting a mostly (quasi-)diagonal texture for models with a low flavor breaking scale Λ f . We argue that many of the popular flavor models in the literature designed to explain the fermion masses and mixings are not suitable for reproducing the observed discrepancy in (g − 2) µ , which requires a delicate balance of maintaining a low flavor scale while simultaneously satisfying strong LFV constraints.

Wrinkles in the Froggatt-Nielsen mechanism and flavorful new physics

“…See refs. [37,50,81,[109][110][111][112][113][114][115][116][117][118][119][120][121] for other solutions to this anomaly, including attempts at embedding the solution in a FN construction. -this conclusion remains unchanged for the other possible charge assignments enumerated in table 1.…”

Reach and complementarity of $$\mu \rightarrow e$$ searches

“…The reach and complementarity of μ → eγ , μ → e ēe and μA → e A transitions have been explored from various perspectives. Numerous authors have investigated model a e-mail: s.davidson@lupm.in2p3.fr (corresponding author) b e-mail: echenard@caltech.edu preferences and predictions for correlations among CLFV observables [20][21][22][23][24][25][26][27][28][29][30]. An early model-independent analysis was performed by de Gouvea and Vogel [31], using a simple effective Lagrangian to describe NP effects.…”