Generalized Landau Yang Theorem

TL;DR

This paper extends the Landau Yang theorem to supersymmetric theories, showing conditions under which its constraints can be evaded, including effects of photon mass and Stueckelberg terms, with implications for particle decay processes.

Contribution

It generalizes the Landau Yang theorem to supersymmetric contexts and identifies mechanisms that can bypass its restrictions.

Findings

The theorem can be evaded if the photon has a non-zero mass.

Supersymmetric selection rules can be bypassed via Stueckelberg mass terms.

Implications for decay processes involving photons and photinos are discussed.

Abstract

Landau Yang theorem is well known for the past several decades. It prohibits the decay of a massive spin 1 particle to two photons. This emerges simply from the representation theory of the Poincare group and Bose Statistics. It does not require any action or Lagrangian. We generalize this theorem to theories with supersymmetry (SUSY) which disallows even decay to two photinos (Majorana fermions) as well as the decay of a zino to a photon and a photino. We will prove that if the photon has a mass, howsoever small, this theorem can be evaded. We also show that the supersymmetric selection rule above can also be evaded through the Stueckelberg mass term. Further interesting implications are also pointed out.