Constraints on leptoquarks from lepton-flavour-violating tau-lepton processes

Abstract

Leptoquarks are ubiquitous in several extensions of the Standard Model and seem to be able to accommodate the universality-violation-driven $B$-meson-decay anomalies and the $(g-2{)}_{\mu }$ discrepancy interpreted as deviations from the Standard Model predictions. In addition, the search for lepton-flavour violation in the charged sector is, at present, a major research program that could also be facilitated by the dynamics generated by leptoquarks. In this article, we consider a rather wide framework of both scalar and vector leptoquarks as the generators of lepton-flavour violation in processes involving the tau lepton. We single out its couplings to leptoquarks, thus breaking universality in the lepton sector, and we integrate out leptoquarks at tree level, generating the corresponding dimension-6 operators of the Standard Model Effective Field Theory. In Ref. [1] we obtained model-independent bounds on the Wilson coefficients of those operators contributing to lepton-flavour-violating hadron tau decays and $\ell$-$\tau$ conversion in nuclei, with $\ell =e,\mu$. Hence, we use those results to translate the bounds into the couplings of leptoquarks to the Standard Model fermions.

29 pages, 1 figure, 6 tables; v2: minor changes, typos corrected, conclusions unchanged, version published in JHEP

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Cited by in corpus (6)

• Marriage between neutrino mass and flavor anomalies
• Snowmass 2021 White Paper: Charged lepton flavor violation in the tau sector
• A neutrino window to scalar leptoquarks: from low energy to colliders
• Revisiting the Scalar Leptoquark ($S_1$) Model with the Updated Leptonic Constraints
• Search for lepton-flavor-violating ${\tau }^{-}\to {\ell }^{-}{K}_s^0$ decays at Belle and Belle II
• Rare decay $t\to c\gamma \gamma$ via scalar leptoquark doublets