Momentum Dependent Vertices $\sigma \gamma \gamma$, $\sigma \rho \gamma$ and $\sigma \rho \rho$ : The NJL Scalar Hidden by Chiral Symmetry

Abstract

We calculate the momentum dependence of three particle vertices $\sigma \gamma \gamma$, $\sigma \rho \gamma$ and $\sigma \rho \rho$ in the context of a Nambu Jona Lasinio type model. We show how they influence the processes $\gamma \gamma \to \sigma \to \pi \pi$, $\rho \to \gamma \sigma$ and $\gamma \gamma \to \rho \rho$ and how chiral symmetry shadows the presence of the $\sigma$.

Comments: 9 pages (latex), 5 figures available from the authors, preprint Coimbra 940506, IJS-TP-94/10, accepted for publication in Zeit. f. Physik A