Beyond-leading-logarithmic effects and matching-scale dimension-eight contributions

Study effects beyond leading-logarithmic accuracy in the combined dimension-6 renormalization-group and dimension-8 double-insertion treatment of charged-lepton flavour violation, and include genuine dimension-8 contributions generated directly at the new-physics matching scale.

Background

The paper analyzes the propagation of tau-sector charged-lepton flavour violation into mu-to-e transitions in the Standard Model Effective Field Theory, retaining both dimension-6 renormalization-group effects and dimension-8 operators radiatively generated by double insertions. Its quantitative results are restricted to one-loop, leading-logarithmic accuracy in the MS-bar scheme and assume that no genuine dimension-8 operators are present at the matching scale.

The authors explicitly identify the extension beyond these assumptions as unresolved future work. Such an extension would require calculating effects beyond the leading logarithms and incorporating dimension-8 Wilson coefficients generated directly when the ultraviolet theory is matched onto the SMEFT, thereby testing the robustness of the reported indirect constraints on tau-flavour-violating operators.