Bounds on Lorentz-violating Yukawa couplings via lepton electromagnetic moments

TL;DR

This paper investigates how Lorentz-violating Yukawa interactions affect charged leptons' electromagnetic moments, deriving bounds on Lorentz violation parameters from current experimental data.

Contribution

It provides the first explicit calculations of Lorentz-violating effects on lepton electromagnetic moments and estimates new bounds from experimental measurements.

Findings

Electron EDM bounds as strict as 10^{-28}

Muon magnetic moment bounds as strict as 10^{-14}

Tau electromagnetic moment bounds as strict as 10^{-6}

Abstract

The effective-Lagrangian description of Lorentz-invariance violation provided by the so-called Standard-Model Extension covers all the sectors of the Standard Model, allowing for model-independent studies of high-energy phenomena that might leave traces at relatively-low energies. In this context, the quantification of the large set of parameters characterizing Lorentz-violating effects is well motivated. In the present work, effects from the Lorentz-nonconserving Yukawa sector on the electromagnetic moments of charged leptons are calculated, estimated, and discussed. Following a perturbative approach, explicit expressions of leading contributions are derived and upper bounds on Lorentz violation are estimated from current data on electromagnetic moments. Scenarios regarding the coefficients of Lorentz violation are considered. In a scenario of two-point insertions preserving lepton flavor, the bound on the electron electric dipole moment yields limits as stringent as $10^{-28}$, whereas muon and tau-lepton electromagnetic moments determine bounds as restrictive as $10^{-14}$ and $10^{-6}$, respectively. Another scenario, defined by the assumption that Lorentz-violating Yukawa couplings are Hermitian, leads to less stringent bounds, provided by the muon anomalous magnetic moment, which turn out to be as restrictive as $10^{-14}$.