Violation of the Landau-Yang theorem from infrared Lorentz symmetry breaking

A bstract Lorentz symmetry forbids decays of massive spin-1 particle like the Z 0 into two massless photons, a result known as the Landau-Yang theorem. But it is known that infrared effects can break Lorentz invariance. Employing the construction of Mund et al. [ 1 ] which incorporated this Lorentz violation, we propose an interaction leading to the decay Z 0 → 2 γ and study the dependence of the decay on the parameter of this Lorentz violation.