Lepton flavor violating meson decays

TL;DR

This paper explores how lepton flavor violating meson decays can constrain effective operators, highlighting the advantages of two-body decay kinematics and the potential of radiative decays for probing new physics.

Contribution

It demonstrates that meson decay studies can effectively constrain LFV operators and introduces the use of specific decay channels to reduce model dependence.

Findings

Two-body meson decays can constrain LFV operator coefficients.

Kinematic restrictions help isolate operators with specific quantum numbers.

Radiative decays offer complementary insights into LFV interactions.

Abstract

We argue that lepton flavor violating (LFV) decays $M \to \ell_1 \overline{\ell}_2$ of meson states $M$ with different quantum numbers could be used to put constraints on the Wilson coefficients of effective operators describing LFV interactions at low energy scales. We note that the restricted kinematics of the two-body decay of quarkonium or a heavy quark meson allows us to select operators with particular quantum numbers, significantly reducing the reliance on the $single \ operator \ dominance$ assumption that is prevalent in constraining parameters of the effective LFV Lagrangian. We shall also argue that studies of radiative lepton flavor violating $M \to \gamma \ell_1 \overline{\ell}_2$ decays could provide important complementary access to those effective operators.