Abstract
We study the two scalar leptoquarks capable of generating chirally-enhanced, sign-dependent contributions to lepton magnetic dipole moments (MDMs) and electric dipole moments (EDMs), $R_2\sim (\mathbf{3}, \mathbf{2}, 7/6)$ and $S_1\sim (\mathbf{3}, \mathbf{1}, -1/3)$. We consider the case in which the electron and muon sectors are decoupled, and leptoquark couplings are assigned complex values. Adopting the coupling ansatz that the electron dipole operator is generated by charm-containing loops, and muon dipole operator by top-containing loops, we find that both minimal leptoquark models remain viable solutions for reconciling anomalies in the muon and electron MDMs, accounting for either of the two current (disparate) electron MDM results from Cs and Rb interferometry experiments. We also examine the correlated corrections to the muon and electron masses generated by these models, and argue that to minimise fine-tuning this introduces an upper bound on viable leptoquark ($\phi$) masses, $m_{\phi}<\mathcal{O}(4)$ TeV. Similar arguments allow us to make a prediction for the upper bound of the muon EDM generated by these models, $|d_\mu|< \mathcal{O}(10^{-22})\; e$ cm, which could be within reach of upcoming experimental programs, including Muon g$-$2 at Fermilab (FNAL), and muEDM at Paul Scherrer Institute (PSI).
Highlights
Lepton magnetic (MDM) and electric (EDM) dipole moments are sensitive precision probes for physics beyond the Standard Model (SM)
S1 and R2 coupling restrictions and the implications for lepton electric dipole moments (EDMs) In Ref. [28], we explored S1 and R2 models to tackle the anomalies in the muon and electron magnetic dipole moments (MDMs)
We have studied the two mixed-chiral scalar leptoquarks S1 and R2, and the interplay between their contributions to MDMs, EDMs and radiative chargedlepton mass corrections
Summary
Lepton magnetic (MDM) and electric (EDM) dipole moments are sensitive precision probes for physics beyond the Standard Model (SM). It is important to note that were the result of Eq (4) to be confirmed, Δaμ and Δae would be of opposite sign, which would be an interesting difficulty to be overcome when searching for a common explanation Such considerations motivate a search for flavor-violating BSM effects to achieve a common solution for these two (putative) anomalies. Corrections in the context of fine-tuning, and present the implications of these constraints on LQ masses and predictions for the generated EDMs. In Sec. IV, we present an overview of important additional constraints, and illustrate the viable parameter space for both LQ models.
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