Lepton flavor violating quarkonium decays

TL;DR

This paper proposes using lepton flavor violating quarkonium decays to constrain effective operators, highlighting the advantages of two-body decay kinematics and the potential of radiative decays for probing new physics.

Contribution

It introduces a novel approach to constrain LFV interactions via quarkonium decays, emphasizing the role of quantum numbers and radiative processes, reducing reliance on single operator dominance.

Findings

Quarkonium decays can constrain LFV effective operators.

Two-body decay kinematics select specific quantum operators.

Radiative decays offer complementary probes of LFV interactions.

Abstract

We argue that lepton flavor violating (LFV) decays $M \to \ell_1 \overline \ell_2$ of quarkonium 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 restricted kinematics of the two-body quarkonium decays 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.