New bounds on lepton flavor violating decays of vector mesons and theZ0boson

Abstract

We give an estimate for the upper bounds on rates of lepton flavor violating (LFV) decays M → µ ± e ∓ of vector mesons M = ρ 0 , ω, φ, J/ψ, Υ and the Z 0 boson in a model independent way, analyzing the corresponding lowest dimension effective operators. These operators also contribute to nuclear µ − e-conversion. Based on this observation and using the existing experimental limits on this LFV nuclear process, we show that the studied two-body LFV decays of vector bosons are strongly suppressed independent on the explicit realization of new physics. The upper limits on the rates of some of these decays are significantly more stringent than similar limits known in the literature. In view of these results experimental observation of the two-body LFV decays of vector bosons looks presently unrealistic.

Mini-review of rare charmonium decays at BESIII

“…By using unitarity considerations, limits on CLFV µ and τ branching fractions [33] have been used to place indirect limits on CLFV J/ψ branching fractions [48][49][50]. In Ref.…”

“…In Ref. [50], the experimental bounds on nuclear µ − − e − conversion are used to place indirect limits on the CLFV J/ψ decays, which are at the same level as those in Ref. [48].…”

“…In particular, it may imply a nontrivial mechanism of self cancellation as discussed in Refs. [48][49][50], which are considered as unnatural.…”

Z lepton flavour violation as a probe for new physics at future $$e^+e^-$$ colliders

“…Indeed, in presence of new physics leading to Z → i j , low-energy LFV processes are unavoidably induced by the virtual exchange of the Z itself: i → j Z * → j f f , where f is a SM quark or lepton. These processes are subject to strong constraints, which then translate into indirect bounds on LFVZD rates [13][14][15][16]. In this work, we plan to reassess the maximal possible LFV effects in Z decays in a model independent way, in view of the improved present and future searches for muon and tau LFV decays.…”

Search for Lepton Flavor Violation in $Υ(3S)\rightarrow e^{\pm}μ^{\mp}$

“…Using LFV limits from µ-e conversions, Ref. [4] sets an upper bound at 3.9 × 10 −6 . However, it has been noted in Ref.…”