Constraints on ∆L = 2 vector bosons with tree couplings to SM particles

A bstract We investigate phenomenological implications of vector bosons V transforming as (1, 2, -3/2) under the standard model (SM) product gauge group SU(3) C , SU(2) L and U(1) Y . These vector bosons can couple to two SM leptons at tree-level forming dimension-4 operators. These operators dictate V to have two units of global lepton number, ∆ L = 2. The operators generated conserve the global lepton number but can violate generational lepton numbers. We study constraints on the couplings Y of V to SM particles using tree-level processes such as lα⁻→ lβ⁺lρ⁻lσ⁻ l α − → l β + l ρ − l σ − , muonium and antimuonium oscillation, neutrino trident scattering, inverse muon decay, e − e + → l − l + , and also one-loop level processes such as the magnetic dipole moment of a charged lepton and l i → l j γ . Strong constraints are obtained from lα⁻→ lβ⁺lρ⁻lσ⁻ l α − → l β + l ρ − l σ − with | YₑₑYμ e Y ee Y μe ∗ | < 3 . 29 × 10 − 11 ( m V / GeV) 2 , YₑₑYμ e^ ∣ Y ee Y μe ∗ ∣ < 3 . 29 × 10 − 11 ( m V / GeV) 2 and from l i → l j γ with Yτ eYμ τ^ ∣ Y τe Y μτ ∗ ∣ < 3 . 46 × 10 − 12 ( m V / GeV) 2 , YeτYτ μ^ ∣ Y eτ Y τμ ∗ ∣ < 3 . 46 × 10 − 12 ( m V / GeV) 2 , respectively. Interestingly, the imaginary part of the coupling constant in our model induces CP violation, which is constrained by experimental limits on the electric dipole moment.