RGE effects on the LFV scale from meson decays

Abstract

We consider the lepton-flavor violating (LFV) lepton-quark dimension-6 operators and analyze their contributions to the LFV leptonic decays of vector, pseudoscalar, and scalar neutral mesons $$M\rightarrow \ell _1 \ell _2$$ M → ℓ 1 ℓ 2 as well as to $$\mu (\tau ) \rightarrow \ell ee, \ell \gamma \gamma $$ μ ( τ ) → ℓ e e , ℓ γ γ decays. These operators contribute to the purely leptonic processes via quark loop. On the basis of quark-hadron duality, we relate these loops to the appropriate meson-exchange contributions. In this way, we extract lower bounds on the individual scales of the studied LFV operators from the experimental and phenomenological limits on the leptonic decays of mesons and leptons. As a byproduct, we shall obtain new limits on the LFV leptonic decays of flavored mesons from the experimental bounds on the three-body lepton decays. We study the effects of QED and QCD radiative corrections to the LFV lepton-quark operators in question. We derive for them the one-loop matrix of the RGE evolution and examine its effect on the previously derived tree-level limits on these operators. We show that the QED corrections are particularly relevant due to operator mixing. Specifically, for some of them the limits on their individual LFV scales improve by up to 3 orders of magnitude.

Lepton flavor violating decays of vector mesons in the MRSSM*

“…All the direct bounds in V → l 1 l 2 new physics scenarios were smaller than the indirect bounds in Ref. [20]. The limits on BR( ) in the MRSSM were more than ten orders of magnitude smaller than the current limits or future experimental sensitivities [24,27,29,72].…”

“…Using an effective field theory, the data in Ref. [20] were obtained from the recast of high-dilepton tails at the LHC for the left-handed scenario, where dipole operators were not considered. The expressions for BR( ) in Ref.…”

“…The expressions for BR( ) in Ref. [20] were the same, except for a few adjustments (e.g., mass, decay constant and full width). Since the mass, decay constant and full width for are very close to , the bounds for were on the same level as .…”